Säsong 4・DI Max Arnold and DS Layla Walsh return to uncover the deadly secrets and hidden motives behind the most powerful families and elite institutions in Chelsea. But as the cases grow darker, so do the personal challenges in their own lives.

Fem vänner beger sig in i Thailands grottsystem Djävulskäften, men upptäcker snart att något livsfarligt jagar dem under ytan.