Having been frustrated in her previous efforts to knock off the Scorpio crew, Servalan (Jacqueline Pearce) hires a chameleonlike professional assassin named Cancer (John Wyman). In their efforts to get to Cancer before he can get to them, the crew members inadvertently cause the death of the slave Nebrox (Richard Hurndall). Another slave, the beautiful Piri (Caroline Holdaway), becomes the romantic bone of contention between Avon (Paul Darrow) and Tarrant (Steven Pacey) -- but there's something deadlier than an amorous rivalry at work here. "Assassin" originally aired on November 9, 1981. ~ Hal Erickson, Rovi