Sæson 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 venner tager ind i Thailands Djævlens Gab-huler kun for at opdage, at noget dødbringende jagter dem under vandet.