The fifth and final season of this supernatural drama begins with the apparent loss of Audrey (Emily Rose), who seems to be gone for good after having transformed into the wickedly evil Mara. This leaves hometown heroes Nathan (Lucas Bryant) and Duke (Eric Balfour) questioning whether it's feasible to get their favorite mystery woman back, or if they should terminate Mara before she makes life even worse with her ruthless and devious tactics. Eventually, Mara is separated from Audrey---it's just too bad freedom comes with some significant costs. First and foremost, Audrey is no longer immune to the Troubles, plus she's now constantly plagued with physical weakness. Meanwhile, Duke has serious problems of his own when he discovers he's brimming with too many Troubles and will literally explode if he absorbs any more, which is something Mara manipulates to her advantage. At the same time, a CDC epidemiologist named Charlotte Cross (Laura Mennell) brings hope of a cure to Haven, but there's something she's hiding from her new friends. And later in the season, William Shatner joins the cast in a pivotal recurring role.