When the body of a teenage girl who went missing at the turn of the millennium is found at a building site off the M1 motorway, four men are placed under the spotlight and their relationships are tested to the limit.
Cassie and Sunny learn that Hayley, who was strangled, was a twin with sister Jessica before they are given a lead linking her to a holiday let where she worked. Having been cleared of malpractice Tim helps the fragile Chris when his old school-friend is burgled though there is good news for Chris from girlfriend Jamila. Pete has no such luck as his fraud is discovered whilst James tries to understand why his son Elliot wants a sex change operation. Then one of them receives a visit from the police.
Mel Hollis's account convinces Cassie that all four men were lying, particularly Pete, whose criminal past makes him the prime suspect and ends his marriage. However Tim's first wife Derran - who stayed at the cottage let with him - paints a less than flattering picture of him whilst Chris's estranged daughter Maya also reveals her father's dark secret. Cassie loses the file on Pete as he prepares to leave the country, having passed on a message about Elliot but Sandra Rayworth's toxic web-site marks him out as a victim.
Following the murderous attack on Pete Sandra Rayworth is charged with incitement. Cassie finds evidence to incriminate Elliot, though only fifteen at the time of Hayley's death, but James quizzes him and brings him to the police, who dismiss him from their enquiries. Chris makes a startling confession whilst Tim's daughter Emma learns the truth about her father's violence from Derran just before an arrest is made for Hayley's murder.
One suspect is now dead and another in custody but evidence found at his flat is dismissed by Mrs Reid as not belonging to Hayley. However it does connect to another unsolved murder and a shocking admission follows, finally closing the case. Meanwhile the remaining two men find positive support through two women in their lives, ending their torment.