S1E12 - The Shooting Star
Gent takes Darien to view the star engine, which turns out to be something much more than an engine.
Darien overhears a tense conversation between Dragon-Eye and Bluebeard. Later, Gent takes him to the engine room.
The engine emits a siren song that draws Darien in. When he touches the engine, it reveals a moment from the deep past of Six.