The ship has been programmed to self-destruct. The corridors blare and strobe with panic. The only survivor, you rush to the landing craft, the whoosh of the airlock echoing your relief. Small engines thrust you seconds ahead of detonation. The red flare that follows should have sufficed to kill your nemesis, but verb tense is everything. The alien has been one step ahead of you this whole time. Now you share a single placental sac. Even naked, you must be lethal. When the hatch opens, only one of you must emerge.