A delivery driver is killed, and a trace of his movements places him at a pub that his wife frequents. She has a motive-but she's an alcoholic and can't remember if she killed him or not. When David doesn't turn up for work, Vivienne confronts him.

A boxer confesses to killing her manager, but the detectives think she may be covering for her father. When a suspect accuses David of planting evidence, he's devastated to realize the team has doubts, and he makes a decision about his future.

When Major Len Miller is found dead at the bottom of his stairs, a bloody fingerprint implicates his grandson. As David and Vivienne shed light on a dark secret from the major's past, they also must deal with the fallout from their indiscretion.

Jed and Ryan encounter a familiar face at Grace's funeral, while Kate learns disturbing revelations about her grandfather.

While Sadie and Jed strike up a passionate affair, Ryan tracks down a mysterious old woman he's seen wandering the grounds.

Molly is haunted by the figure of a burning man, but things get intimate with Ryan when he is forced to protect her.

A groom is killed at his bachelor party, and the man who reports the crime is the ex-husband of the bride. The detectives race to find the missing 18-year-old best man, who may have been the killer or another victim.

DC Rob Brady and Trainee DC Billie Fitzgerald respond to a gruesome scene: a man found stabbed multiple times and left hanging from a tree. DS Vivienne Cole expects to lead the investigation but is shocked when DI David Bradford takes over, as he has been on leave since the disappearance of his wife.

When schoolboy Luis Moretti is found dead in a lake, the detectives learn of a potential connection to the recent suicide of a young girl. Meanwhile, DS Vivienne Cole tells David that she believes Detective Chief Superintendent Mulgrew was behind the threat to Rob's family, and she reveals her past relationship with the chief.

After off-duty police officer Sgt. Ian Durrant finds a dead man at the wheel of his van, the detectives link the victim to a woman who was killed while in police custody. As DC Rob Brady was the one who discovered her dead, the case affects him deeply. When Trainee DC Billie Fitzgerald finds a connection to a murdered young cop, DI David Bradford suspects the killer could be a police officer.