Generations

Read Generations Storyline:

A mysterious star map 
On an Outer Rim moon, Captain Malcolm Reynolds ends a card game the lucky winner of an old map covered in mysterious symbols. The former owner insists it's worthless; back on Serenity, River Tam is able to interpret it.

An ancient legend
River claims the map points the way to one of the Arks: legendary generation ships that brought humans from Earth- That-Was to the 'Verse. The salvage potential alone is staggering.
A drifting relic
As the crew approach the aged floating ship, they find it isn't quite as dead as it first seemed. The closer they get, the more agitated River becomes. She claims something is waiting on board, something powerful, and very angry...