The Doctor and Peri arrive aboard the USS Eldridge and witness the results of the infamous Philadelphia Experiment, leading to journey to an alien universe.
Author Ingrid Pitt was also an actress in the classic series stories The Time Monster and Warriors of the Deep. She and her husband Tony Rudlin were asked to write this story while she was working on Warriors of the Deep. The script was originally titled The Macro Men. Pitt died five months after the release of this audio.
