The fourth series of the drama about a supernatural seductress opens in a world where all memories of Bo (Anna Silk) have been expertly erased. When Kenzi (Ksenia Solo) and Dyson (Kris Holden-Reid) do eventually come to remember their friend and that she needs their help, Dyson has to travel between dimensions to find her. Back home, trick-dealing Massimo the Druid (Tim Rozon), the unscrupulous Vex (Paul Amos) and wicked Evony (Emmanuelle Vaugier) give the trio trouble. But it's the Una Mens that make life particularly difficult, beginning when they declare that they are no longer interested in Bo, contending she's aligned with the Dark. While Bo sets out to prove she's still a free agent, Kenzi finds romance with Hale (K.C. Collins), and appearances by Krampus, merpeople, zombies and George Takei keep everyone on their toes.