The Orpheus crew's quest for renewable energy has led them into danger. They're trapped on Volos, a Russian submarine, and its nuclear reactor is dangerously overheating. Whoever shuts it down will be exposed to lethal radiation.

Cast: James Nesbitt, Goran Visnjic, Sacha Dhawan, Richard Brake, Minnie Driver, Tom Wlaschiha, Nick Nevern, Tobias Menzies, Orla Brady, Vera Graziadei, Dan Li, Nigel Whitmey, Molly Jones, Sinéad Cusack, Goran Kostic