Mary Kills People

It's been eight months since Mary and Des framed Grady, their drug dealer, for the deaths of their patients. While Des has been serving prison time to protect his partner, Mary's been managing surprisingly well on her own – she's found a new supply of pentobarbital in Mexico, her business has continued to thrive thanks to Annie's ability to source terminal clients in need, and her ex-husband Kevin has moved in and taken on half the parenting duties following a messy break-up with Louise. Though Jess still suspects that her mother is hiding something, Mary has been working diligently to keep her professional and private lives separate. But secrets can only be hidden for so long when Olivia – a mysterious woman with a connection to Mary and Des – comes to them with a deadly request.

When Olivia attempts to blackmail Mary, she is drawn deeper into a deadly game of cat and mouse.

Mary and Ben join forces; Travis reveals a crucial detail about Ben's investigation.

Following the disappearance of Travis, Des worries that he and Mary may have crossed a moral line from which they can never return. After jeopardizing Ben's investigation of Olivia, Mary tries to make amends, which has repercussions for a patient in dire need.

Ben forgives Mary; Mary and Des move forward with the death retreat.

Mary decides to wear a wire; Des and Nicole prepare for Brendan's death.