Plot

The movie is a farce about a mentally unstable advertising executive, Denis Dimbleby Bagley (played by Grant), who suffers a nervous breakdown while making an advert for pimple cream.

Ward plays his long-suffering but sympathetic wife. Richard Wilson plays John Bristol, Bagley’s boss.

Bagley has a crisis of conscience about the ethics of advertising, which leads to mania.

He then develops a boil on his right shoulder that comes to life with a face and voice.

The voice of the boil, although uncredited, is that of Bruce Robinson. The boil takes a cynical and unscrupulous view of the advertising profession in contrast to Bagley’s new-found ethical concerns.

Eventually, Bagley decides to have the boil removed in hospital but moments before he is taken into the operating room, the boil quickly grows into a replica of Bagley’s head (only with a moustache) and covers Bagley’s original head, asking doctors to lance it, which is done since nobody has noticed the switch from left to right nor the new moustache.

Bagley, now with the boil head, moustache, and personality (the movie’s third personification from Grant after the stressed executive and the raving lunatic) returns home to celebrate his wedding anniversary, with the original head merely resembling a boil on his left shoulder.

The “boil” eventually withers but doesn’t die, yet Bagley resumes his advertising career rejuvenated and ruthless, although without his wife, who decides to leave his new cruel persona.