"Suggested" by his own novel, Ticket To Ride, Potter's screenplay has Alan Bates as a middle-aged illustrator seemingly somewhat short on marbles, plagued, as he still is, by a malevolent alter-ego one assumes to be the secret friend he invented during a lonely childhood locked up in the crumbling pile he now shares with a young woman (Bellman).
So warped is Bates' mind, however, that Bellman might be his wife, or a prostitute he meets at a hotel, or his wife acting out the sexual fantasies her husband has engendered. What with Bates lurching about, axe in hand, and muttering "Filth, filth, kill the bitch" every other scene, and Bellman, the object of his schizophrenic ramblings, palely whimpering as downtrodden wifey one minute and vamping it up as a hooker with half a brain the next, this has all the makings of a Hammer Horror, given a better script and more imaginative direction, rather than the dark, psychological thriller it purports to be.
Bates nevertheless camps it up with gusto while Frances Barber and Tony Doyle do their best with stricty limited roles as the sexually predatory neighbour and estate agent respectively.