Gordon Heath plays a genius scientist named Gregory who bets two of his associates that in using only his natural brain power that he can escape from a maximum security prison in 7 days' time.
The mystery resides in what the man does and how he does it to accomplish his experiment.
Ian Martin plays the warden, and Russell Horton is one of the prisoners.

One of the best shows of the series with a unique approach and a logical resolution that makes total sense. Definitely a story that makes you think!