When did You Start to Stop Seeing Things? is the tenth episode of the popular 1969 ITC British television series Randall and Hopkirk (Deceased) starring Mike Pratt, Kenneth Cope and Annette Andre. The episode, directed by Jeremy Summers, was first broadcast on 23 November 1969 on the ITV.

Jeff is hired by a company based in Metropolis House to find out who is leaking information for use on the stock market. Unfortunately matters are complicated when a financial adviser named Charles Tully is murdered in a car park late at night and Randall is implicated. Jeff then goes on to arrange traps for the personnel director Holly and managing director Hepple, executing them both.

Meanwhile, Marty is very concerned that Jeff can no longer see or hear him and is acting out of character, so ventures to Harley Street to seek the advice of psychiatrist and hypnotist Sir Oliver Norenton. He speaks to a patient under hypnosis, getting them to tell Norenton to visit Randall and give him treatment.

As Jeff continues to act brutally killing several of the financial personnel and sexually assaulting Jeannie, Marty eventually realises that the real Jeff has actually been kidnapped and a masked double named Hinch has been put in his place. Using more hypnotised patients to contact Jeannie, he uncovers the address of where the villains are hiding - The Manor House, Milton Vale - put there by the company's general manager, Mr. Laker, the inside perpetrator. Marty discovers Jeff imprisoned in the cellar of the house and rigs an escape for Jeff by distracting the professional killer who is guarding the house by smashing a vase in the hallway. Jeff overpowers the man but is then knocked unconscious by Jeannie with a mace, who believed him to have murdered the men that the fake Randall killed. They are about to be killed, in one of their most impossible situations yet, Marty returns to the psychiatrist Norenton, who is in the process of putting himself in a trance after hearing all his patients talk about Randall to attempt to understand why it had happened.

...
Wikipedia