Jeff's car is stolen and used in a robbery, whereby the perpetrators use hypnotic suggestion to rob wealthy upper class businessmen.
Concerned for Jeff's mental health after hearing him talking to himself (in reality, Marty), Jeannie's sister Jenny places a hidden tape recorder in a drawer in his office to capture him doing it again. When they have a "one-sided" conversation on tape, Jenny and Jeannie arrange to send Jeff to a Dr. Conrad at the Lambert Clinic Nursing Home.
Retaining Jeff against his will and filling him with illegal drugs, it happens that Conrad is the mastermind behind the robberies, in league with a criminal known as William Smart, who enters each household and robs the customers as they are hypnotised by telephone.
Dr. Conrad uses hypnosis to erase Marty from Jeff's mind, but Marty manages to impersonate Dr. Conrad's voice in order to communicate with Jeff. He instructs Jeff to break out of the facility and eventually the police are led there, arresting Dr. Conrad and his associates. Jeff claims that his "talking to himself" was all part of an elaborate ploy to get him placed in the hospital, and celebrates his success by taking the two sisters to dinner.
Jeff Randall initially collapses unconscious after being lightly thrown against a door by Phillip and Pentonville, the two hospital heavies, but later under hypnosis he beats some five men in fights, including Doctor Conrad.
Marty is seen pulling objects such as a door towards Jeff's head by inhaling in this episode. When teleporting to a specific location he is also heard to say "Made it! My sense of direction is improving!"
In this episode Jeannie's presumably younger sister Jenny is introduced. Like actress Annette Andre who portrays Jeannie she is also real life Australian, and the likeness between them is similar. Currently unemployed, she's staying with Jeannie from outside London, what she terms "the sticks".
The exteriors for The Lambert Clinic Nursing Home were shot at The Grocer's Institute on Grange Lane, Letchmore Heath. Whitty's home exterior was filmed at a private house named Aragon on Aldenham Road, Letchmore Heath. Arthur Phillips house was shot on the exterior standing backlot sets at ABC Elstree studios, Borehamwood.
A finished print was completed by late August 1969. It is listed as episode 22 in ITC publicity.