In the third episode of the four-part story "Terminus," young Turlough (Mark Strickson), acting on orders from the Black Guardian (Valentine Dyall), has locked the TARDIS into the flight pattern of a space stration peopled by victims of the dreaded Lazar's Disease. The Doctor (Peter Davison) tries to deal with this contingency, as well as a greater danger: An unstable thrust engine which may explode at any minute -- thereby destroying the entire Universe. First telecast on February 23, 1983, "Terminus, Episode 3" was written by Stephen Gallagher. ~ Hal Erickson, Rovi