"Never Trust a Ghost" is the fourth episode of the 1969 ITC British television series Randall and Hopkirk (Deceased) starring Mike Pratt, Kenneth Cope and Annette Andre.
One evening, whilst idly passing the time away, Marty witnesses an ambush outside the home of a wealthy civil servant, James Howarth.
Mr Howarth arrives home and is threatened by a man waiting in the street and forced into his own house, where he is promptly shot.
The killer then immediately gets on the telephone and tells somebody that his mission was a success and that there were no witnesses (unaware of Marty's presence of course) and reveals himself to be a Mr Rawlins in the process.
He eventually convinces a reluctant Jeff to pay the Howarths another visit with the ostensible excuse that he is apologising, whilst Marty does some investigating.
Mrs Howarth answers the door and can't believe that Jeff would have the audacity to call again, however he pushes his way past her and rather rudely takes a seat in the living room, without being asked.
Mrs Howarth calls the police and Jeff is arrested by a gleeful Inspector Clayton who is keen to throw the book at him.
Clearly exasperated by Marty's continual false leads Jeff decides to seek help from a psychic expert called Professor (also Dr) Plevitt and asks him if it's possible for a ghost to tell lies.
Whilst Jeff is doing this the spies plot on killing him after they realise that the police have failed to apprehend him yet again.
At this time the imposters reveal that they are spies for a foreign (undisclosed) country and that they chose Mr Howarth to impersonate as he is in charge of salaries for various British Intelligence agencies and, as such, he has access to every undercover agent's details used by the UK.
The imposter Howarth has been busy photographing all the important documents whilst he has had access to his place of employment.
Stock footage depicting London at night at the start of the episode consisted of shots of Berkely Street, Lambeth Pier and the Houses of Parliament.