Martin and Hayley persuade Carl to go undercover to get a confession from Kate, hoping she will confess to the murders of both Anna Boruk and Gemma Hillman. The surveillance team prepare for their biggest operation yet with all eyes on Westbury Street and the Tuckman house. Martin prepares a nervous Carl to coax a confession from his own wife. But just as Martin and Stella believe they are finally edging closer to the truth, Martin is forced to intervene when an unexpected move from Greg leads to devastating consequences. A startling discovery leads Martin to finally uncover the events of the night Gemma disappeared and the ground falls from beneath his feet.