A rogue submarine captain pulls together a misfit crew to go after a sunken treasure rumored to be lost in the depths of the Black Sea. As greed and desperation take control on-board their claustrophobic vessel, the increasing uncertainty of the mission causes the men to turn on each other to fight for their own survival.

After the tragic death of her husband, a soldier posted to Afghanistan, Bryony tries to build a new life for herself and her young son, James. Struggling with her own grief she fails to notice that James has become secretive and withdrawn, spending hours alone playing out death scenes with his toys. When things start to go missing and furniture is smashed Bryony blames James but when she confronts him she finds herself facing a reality more terrifying than any nightmare. As her world crashes around her Bryony realises that unless she can find a way to reconnect with her son she and James will be separated for ever.