Detective Inspector Marnie Rome and her partner Detective Sergeant Noah Jake are investigating the recent discovery of two dead boys in a bunker beneath a London garden. Terry and Beth, under whose garden the bodies were discovered, have two children of their own and are also fostering a difficult boy named Clancy. Clancy reminds Marnie of her foster brother Stephen, who murdered her parents. Is Marnie's past blinding her to the truth? Only one thing is certain: when Terry and Beth's biological children vanish, Marnie can't waste a moment finding them.