In season 2, Mary plummets deeper into the criminal world as she searches for a steady supply of pentobarbital, the highly regulated and highly lethal "death drug." As she becomes more entangled in her illegal work, Mary continues to risk her family and career as she tries to keep her worlds separate. But when the mysterious Olivia Bloom approaches Mary and her partner Des with a lethal request, and when Mary crosses unexpectedly with Detective Ben Wesley, she realizes her secrets can only be hidden for so long.