Sarah's perfect life is turned upside down when she discovers that her husband is having an affair with her best friend, Charlotte. The Bad Mothers: Maddie, Danielle and Bindy encourage Sarah's small acts of revenge. Danielle starts to have feelings for hunky teacher, Luke Jasic. Maddie sees red when Charlotte's daughter steals Max's baby chick. As revenge, she kidnaps Charlotte's dog, but when she returns the hostage, she finds Charlotte dead. The Bad Mothers never liked Charlotte, but this wasn't the outcome they wanted! Especially as police are questioning Sarah. Sarah's relieved when she's released, but now her husband Anton is arrested for Charlotte's murder...

Sarah's efforts to get Anton released reveal that he has put them deeply in debt, but surely he's not a killer? Danielle is convinced that Charlotte's widower, the brooding Kyle, is a more likely suspect. Sarah gets her hopes up, but Bindy finds Kyle has an alibi. Sarah starts to fear that her husband is guilty, then finds evidence that Kyle's alibi is false. Maddie's anger with her unreliable ex causes her to find that Jesse is in a new relationship. Bindy finds that her parents are selfishly abandoning her. She will have to care for her daughter! Sarah finds her most loyal support is from her new unlikely friends, the Bad Mothers.

Sarah and Kyle are forced to bond over their kids. Xavier is failing at school and refusing to visit Anton in jail, and Julius seems to be suffering from depression. Danielle helps Sarah out with the restaurant and finds it's being mismanaged. She contemplates a return to her old career. Maddie's war with her ex gets ugly and Maddie fears she can't afford the fight.

Tom is threatened by Danielle's return to work, while Luke is supportive. Danielle is tempted to stray, but a family crisis makes Danielle call off the liaison. Maddie has a new contender in the battle for custody: Connor, her son's sperm donor. Sarah discovers that Julius thinks he is responsible for his mother's death and it was an accident. She hopes this will help Anton, but it doesn't fit the police facts. Sarah supports Julius and Kyle is grateful. Bindy's daughter becomes an Instagram sensation and Bindy exploits her for profit.