Lindsay, Claire and Jill cautiously welcome a new member to the Women's Murder Club, young reporter Cindy. Meanwhile, Lindsay and Jacobi investigate a homicide committed by a serial murderer dubbed "The Vendetta Killer". In their private lives, Lindsay faces up to the past when her ex-husband is brought into her police department in a leadership role, Jill faces a domestic crisis, and Claire struggles to help her husband, who's fighting depression.

Lindsay and Jacobi hunt down a killer who committed a triple homicide on a subway car, and discover a disturbing twist in the killer's motive. Cindy tries to gain the respect of The Club. Jill prepares to move in with Luke. Claire helps Ed through his recovery. Lindsay meets Tom's fiancée.

An NFL quarterback is found dead in his hot tub, with his family believing it was suicide. But the Club think differently. Meanwhile, Lindsay crosses paths with an NFL star who was friends with the dead man.

The Club have 24 hours to stop an innocent man's execution and find the real killer of the woman he was accused of murdering. Meanwhile, Jill discovers corruption in the D.A.'s office, and Lindsay worries that her one night stand with Tom may have resulted in pregnancy.

The Club delve into San Francisco's drag queen community while investigating a murder. Meanwhile, Tom and Heather tie the knot, and Luke finally discovers the truth about Jill and Hanson's affair.