Steve and his group then set off and, after a short rest, the group is introduced: Professor MacGregor (Richard Jaeckel), an anthropologist; Frank and Mandy Young (Jon Cedar and Susan Backlinie), a bickering married couple; a wealthy older woman, Shirley Goodwyn (Ruth Roman) and her son, Johnny (Bobby Porter); Paul Jenson (Leslie Nielsen), an advertising executive and psychopath with an angry, derisive sense of humor; Bob Denning (Andrew Stevens) and Beth Hughes (Kathleen Bracken), a teenage couple; Roy Moore (Paul Mantee), a former professional football player sidelined by cancer; Terry Marsh (Lynda Day George), a television reporter; and Daniel Santee (Michael Ansara), a Native American guide and the steadiest person among them.