Lair of the Sentinels

by Geoff Palmer

  ‘Hi.’

  Alice froze. Her eyes widened as they fixed on him.

  ‘Would you mind picking some rhubarb?’ Em said. ‘I thought I’d do a rhubarb tart for dessert tonight.’

  ‘No. No, of course not.’ Alice dragged her eyes away. ‘I’ll ... just get a basket.’

  She scuttled off and Em followed her in.

  ‘What was that all about?’ Norman said.

  Tim shrugged.

  ‘She has a built-in dork detector,’ Coral said. ‘I guess she spotted one.’

  ‘Ignore her,’ Tim said. ‘She’s weird.’

  Norman glared at Coral. ‘Yeah, and so is your aunt.’

  They settled in the shade of a brightly coloured umbrella, feeling the warmth of the clear blue day around them. Tim and Coral almost drifted off, but Norman was restless. There was a rustling from the undergrowth near the house and a large black and white cat emerged, peering left and right before trotting over to join them. Tim opened one eye and looked down as her tail brushed past his arm. ‘Hello scaredy-cat.’ He reached out a hand. ‘Finally got your courage back?’

  Smudge turned and settled on the lawn beneath his seat.

  ‘Wonder what Albert’s got in mind,’ Norman said.

  ‘Dunno.’

  ‘Tell you what I don’t get,’ Coral said, opening one eye. ‘That explosion only took out their escape pod. They’ve still got a mothership up there. It must have more than one landing craft, so why not just get it to send another one?’

  ‘That’s the problem,’ Tim said. ‘Sending the message. They need a really powerful transmitter to do that.’

  ‘But we build transmitters all the time. And we send out space probes. How hard can it be?’

  ‘How far away is their mothership?’ Norman asked.

  ‘About seven hours at the speed of light.’

  ‘There’s your problem.’

  ‘What do you mean?’

  ‘Light travels about a billion kilometres an hour, so that means it’s seven billion kilometres away. You’ll need a really big transmitter to send a signal that far. And a really accurate one to pinpoint a spaceship.’

  ‘How big?’

  ‘NASA use the Deep Space Network for their interplanetary craft. They’ve got stations in America, Australia and Spain. The dish near Canberra’s seventy metres across.’

  ‘Seventy metres?’

  ‘You could probably get away with something half that size if you aimed it really carefully, with computer controls and everything.’

  ‘Forget computers,’ Tim said. ‘There’s no way they could ever build something that big. The raw materials alone ... And even if they could, someone’s bound to notice a thirty-five metre dish, even round here.’

  ‘What about all their advanced technology?’ Coral said.

  ‘Apparently they could make one the size of a suitcase — which is what the escape pod used — but it needs all sorts of exotic materials that could take months to refine. Stuff you’d need a chemistry lab to extract, provided you could find the right raw materials in the first place.’

  ‘So they really are stuck.’

  ‘Maybe not,’ Norman grinned. ‘Remember, Albert said he’s got a plan.’

  6 : Perfect Spies

  The shortcut to the reserve wasn’t much of a shortcut. It involved climbing fences, jumping the stream that marked the edge of the Townsend property, and following a winding track through the bush, but it was more interesting than the straight stretch of gravel road that led from the entrance of the farm. Smudge followed them part of the way, trotting along behind like a well-trained dog, and showed every sign of wanting to continue past the rushing stream if only someone would lift her across.

  ‘Go home, you’ll get lost,’ Tim said, waving her away.

  The track emerged on the seaward side of the reserve behind a low wooden toilet block at the bottom of the circular camping area. The patch of grass in front of it was empty apart for the Eltherians’ car and caravan, parked at the opposite end, exactly where they’d been the day before.

  At first, nothing looked different. The space where the caravan sat was backed by long grass, bush and tall trees, but looking higher they could see the tops of the trees were scorched and broken. Many were missing branches, as if a barber had shaved the backs of their heads.

  They heard Ludokrus’s raised voice in the distance. Albert snapped something back. Ludokrus replied. The sounds reached them, but not the words.

  ‘We might be a bit early,’ Tim said. ‘Let’s give them another few minutes and check out the crater.’

  They moved on, keeping out of sight.

  The damage was more obvious the closer they got to the centre of the explosion. The dense vegetation was scorched and torn. Every tree around the crater’s edge had been snapped and flattened. Tim tried to imagine it from the air. It would be like a child’s drawing of the sun. An empty circle with lines radiating from the edge.

  The crater itself was ten metres across and three deep, its steeply sloping sides streaked with glassy fragments of rock fused by the tremendous heat of the blast.

  ‘Wow!’ Norman muttered.

  Tim looked at the wasteland around them. It didn’t seem possible that this time yesterday it had been dense bush teeming with bird life. That where he stood now had been the entrance to a glade of waist-high ferns that hid the little Eltherian ship. He and his sister had explored some of the area in the bodies of mice, marvelling at the richness and variety of life in even a tiny patch of ground. Now it was all gone.

  ‘I wonder if Pipi and Paua are OK,’ Coral said. She’d been thinking about the mice too.

  ‘They should be,’ Tim said. ‘Alkemy let them go near the caravan.’

  Norman edged into the crater, picking up and studying fragments of fused rock as he made his way towards the epicentre.

  ‘Is it still radioactive?’ Coral said loudly.

  He squawked and bounded out again to find her doubled-up with laughter. ‘I wish I’d got that on my phone,’ she said. ‘The look on your face!’

  * * *

  Tempers had cooled by the time they returned to the reserve. One side of the awning had been rolled up to let in light and air, and Albert was busy at a makeshift table. Alkemy and Ludokrus were in the caravan, unpacking and arranging the last of their things.

  They spotted the smell as they approached. An odd, dry odour like burnt coffee. It grew stronger, and by the time they reached the caravan it was almost overpowering. Alkemy came down the steps fanning a piece of cardboard.

  ‘What is that pong?’ Coral said.

  Albert, stooped over the table, lifted a metal rack from a square plastic trough and set it to one side. As he did so, another wave of the burnt coffee smell washed over them and they all screwed up their noses.

  ‘Another reason to move away from the farm,’ he said, glancing at Ludokrus.

  He took a grey cube from the rack and inspected it. It looked like a dice without numbers on the sides. He nodded in satisfaction. ‘Good. Let me neutralise this stuff.’

  He poured a bucket of brown liquid into the trough. There was a faint fizzing sound and steam-like tendrils rose above the surface. The burnt coffee smell thinned immediately.

  ‘Go inside,’ he gestured. ‘Make yourselves comfortable. We need to talk.’

  They squeezed around the caravan’s tiny dining table and Albert set three of the grey cubes in front of them. ‘Scanner blocks,’ he said.

  The cubes measured a centimetre on each side. They had rounded corners, a mottled surface, and a texture that resembled compressed sand. Tim picked one up. It was surprisingly heavy and its sides sparkled faintly in the light.

  ‘A quick build from a quick design, but I think they’ll do the trick. Before we get on to that though, tell me all you know about the Sentinels.’

  Ludokrus crossed his arms. ‘Only what you tell us. Almost nothing.’

  ‘Right, well let me correct that,’ Albert said, p
ulling up a folding chair and settling at the end of the table.

  ‘The Sentinels are agents of the Thanatos. They were sent here to look out for survivors after our ship crashed in your solar system. They’re essentially watchers; a first line of defence sent to shield human beings from outside interference. From people like us.

  ‘In appearance, Sentinels are large slug-like beings that live underground, but they have one unique ability; to work their way into the minds of other creatures. Once in, they see what their host sees and hear what it hears. In short, they’re perfect spies. And given time, they can even gain limited control of their host.

  ‘Sentinels work in pairs and are creature-exclusive, which is to say they can only monitor and direct one person each. We’ve identified one of their hosts, Millicent Millais, the principal of Rata Area School, the one you call Cakeface. There will almost certainly be another, as yet unidentified.’

  ‘Now, you’re aware of the problem we have communicating with our mothership?’ They nodded. ‘We could spend months obtaining and refining the raw materials we need to build a transmitter. My original plan was to move away and do just that, but now the Sentinels know we’re still alive, they’ll pursue us. And they’ll keep pursuing us until they fulfil their mission. So we don’t have the luxury of time any more. We need to move fast and we need to move boldly. We need a transmitter, and it occurs to me that the Sentinels must already have one.’

  The idea took them by surprise.

  ‘You don’t mean ... to copy?’ Coral said.

  ‘No, I mean to use.’

  Ludokrus snorted, ‘You think we can go to them and say, “Please may we borrow this?”’

  ‘There will of course be ... contingencies to manage.’

  ‘Contingencies? You mean like the killer robot? How do we manage him?’

  ‘Things will become clearer once we’ve discovered the Sentinels’ location.’

  Tim gestured at the cubes. ‘So where do these come in?’

  ‘The Sentinels monitor their hosts via direct mental links making them almost impossible to detect. But to control their hosts they have to send them signals in the form of suggestions and subtle directions. That’s what these things pick up.’

  ‘You mean we eavesdrop on them?’

  ‘No, they’re not that sophisticated. But what they will do is pick up those signals, and that will help us pinpoint the location of their transmitter.’ He waved a thumb at the rack in the awning. ‘I’ve made a hundred of these things. The wider we spread them and the more signals they intercept, the more precisely we can locate it.’

  Triangulation,’ Norman said.

  ‘Exactly.’

  ‘Huh?’ Coral said.

  Albert pushed scanner blocks into three into different corners of the table. ‘Imagine these things detect the same transmission, from this point here.’ He tapped his finger on one side. ‘Because they’re not all at the same distance from my finger, they’ll receive that transmission at slightly different times. We know that radio waves travel in a straight line and at a constant speed, so by measuring the angles and distances between the blocks we can pinpoint source of the transmission.’

  ‘OK.’

  ‘The key to this is distribution. We’re talking about tiny differences in the time of reception, so the wider they’re spread, the better. What I’d like Coral and Tim to do is distribute them around here and around the farm. The rest of us — with Norman’s guidance — will do the same around Rata.

  ‘After that, we simply wait for the Sentinels to send instructions to their hosts. The blocks will intercept them, and from that we can locate their transmitter.’

  Norman frowned. ‘But what if the Sentinels send Cakeface after us with a gun or something?’

  ‘They can’t. It doesn’t work that way. If they gave her a direct instruction like that, she’d become aware of them. It would be like having voices in your head. They have to work indirectly, try to make her do what they want without making their presence obvious.’

  ‘How do you mean?’

  ‘Let’s say they wanted you to go into the kitchen. They can’t say Go into the kitchen or you’d become aware of them, so instead they might make you feel thirsty. Then you’d go into the kitchen of your own accord to get a drink.’

  ‘Creepy!’

  ‘And that’s what the scanner blocks pick up?’ Coral said. ‘The You’re feeling thirsty bit?’

  Albert nodded

  ‘What of the second host?’ Alkemy said. ‘You say they work in pair, so there must be one more. But we do not know who.’

  ‘Hopefully, these things will help us pinpoint him or her too.’

  ‘I know already,’ Ludokrus said.

  ‘Eh?’

  ‘What?’

  ‘Who?’

  They all spoke at once.

  ‘Can only be the Uncle Frank. He give us away on the radio. Tell the whole world we are OK.’

  ‘If he was a Sentinel host,’ Albert said evenly, ‘there’d be no need to do that since he’d be communicating with them directly. Besides, I checked the farmhouse and all the out-buildings last night. I’m certain that it’s no one there.’

  ‘How can you be sure?’

  ‘Once they establish a link, the Sentinel portion inside the host’s brain needs regular recharging. They do that by drawing energy from a particular wavelength of light. I’ve checked the farm thoroughly for coloured light bulbs, stained glass windows and that sort of thing. There’s nothing at all that qualifies. It would either have to be a large source in a common area that allows for a slow, steady charge, or a concentrated source in a small space so as to recharge rapidly.’

  Ludokrus raised an eyebrow. ‘What colour is this light? Pink, maybe?’

  ‘Why yes.’

  ‘A shade like sickly pink?’

  ‘How did you know that?’

  ‘And you will get this charge maybe from a room painted in this colour?’

  ‘As long as the host spends several hours a day in there, yes.’

  Ludokrus was silent for a moment. Then he said in a low tone, ‘Why do you not tell us this before?’ His voice had an edge to it. An ominous quality. Like the ticking of a time-bomb.

  ‘I didn’t think it was relevant.’

  ‘You do not think is relevant.’ Ludokrus took a breath. ‘What colour do you think is the office of the Cakeface, the teacher who lure us into a trap and almost get us killed?’

  Albert stared at him.

  Ludokrus slammed his fist on the table. ‘I tell you what is colour; pink, sick pink!’

  ‘You never said—’

  ‘I never say?’ Ludokrus leapt to his feet. ‘How do I know what is relevant? You want I tell you the colour of her stapler or the type of dress she wear? If we know what we are looking for, we would be on our guard. Instead, you tell us nothing. Leave us to be kidnap. Almost we are killed because you keep us in the dark!’

  ‘I’m sorry.’

  ‘Yeah, sorry. That make it better. I feel so good now. No more nighthorse for sure.’ He snorted. ‘If you tell us, warn us, maybe we do not even lose our ship. Now you say we are to walk into the base of our enemy. “Please, may we use your radio?” We see already what these Sentinels can do.’ He pointed round at the others. ‘We are there, not you. We face the killer robot, not you. And when they catch us, kill us, will you say again that you are sorry?’

  Albert said nothing.

  ‘You know what is your problem? I think you spend too long to fix our broken ship. I think the space mould get into your brain and make your wiring misfire. A robot will have more sense!’

  Ludokrus threw down the scanner block and stormed out of the caravan.

  7 : Off Day

  ‘That’s ... not ... possible ...’

  ‘What isn’t? Show me?’

  ‘The Eltherians. They’re still alive.’

  ‘That’s not possible.’

  ‘I just said that! And clearly they are. Look. That’s
what that alarm was trying to tell us.’

  ‘I thought it was music.’

  ‘The Thanatos will make music with our innards if they find out we’ve failed!’

  ‘But what about our ship? It’s coming to take us home. We can’t send it back. That’ll give the game away.’

  ‘We need another Emissary.’

  ‘There was only one killer robot in the local system, and that blew itself up. The nearest local support post is almost a week away. Besides, our ship is due in sixty hours.’

  ‘Then there’s nothing we can do. The Thanatos will find out. We’re doomed!’

  ‘Oh no we’re not. We still have two-and-a-half days before our ship arrives. That gives us two-and-a-half days to finish the job.’

  ‘But how?’

  ‘Any way we can!’

  * * *

  ‘They’re gone,’ Coral said.

  ‘I hear the car.’

  ‘So it’s just you and me.’

  ‘I guess.’ Ludokrus didn’t turn. He stood at the crater rim, hands deep in his pockets.

  ‘For what it’s worth, I thought you were right. If Albert had told us more about what to expect, none of this would have happened.’

  Ludokrus said nothing. Coral unzipped a pocket in her backpack and drew out a water bottle, took a swig then offered it to him. Ludokrus wasn’t thirsty, but this wasn’t about thirst. He took a drink and passed it back.

  ‘Thanks.’ He continued staring down at the crater, then sighed. ‘I feel bad. Should not say that thing to Albert, but he make me mad sometimes. Always with the logic. Always with the secret ’

  ‘You mean about him being as dumb as a robot?’

  ‘Bad thing to say to syntho. They are like real people, only better sometimes. Do not get mad or say dumb thing.’

  Coral remembered what he’d told her of the Robot Liberation Movement. A movement not to free mindless machines from the scrapheap, but to liberate synthos from the term “robot” and give them legal rights. Robots did what they were programmed to do, over and over. Synthos thought about things and had minds of their own.

  ‘You’re just tired and a bit cranky. We all are. None of us got much sleep last night.’