Scientists Culp and Wallach suspect that there is someone other than their research primates inhabiting their polar station.
- Jerrold Freedman
- Christopher Knopf
- ABC Circle Films
- Spelling-Goldberg Productions
Scientists Robert Jones and Frank Enari are dispatched to the Tower Mountain Research Station to replace a colleague, Dr. Vogel. For the past five days, due to a severe snow storm, Dr. Vogel failed to communicate with the base. His last communications with the base betrayed a confused, anxious and delirious man. Concerned about Dr. Vogel's safety and state of mind, the base sends the two replacement scientists to the summit research station via helicopter. The replacement researchers bring along a chimpanzee for the cold weather tests. When they arrive at the summit research station, the two replacement scientists find a ransacked station and no trace of Dr. Vogel.