46-year-old Sunshine Desserts sales executive Reginald Iolanthe Perrin is clearly suffering a midlife crisis. Though not unhappily married to Elizabeth, he calls her mother a hippopotamus and is finding no enthusiasm for marketing his boss C.J.'s latest line: exotic ices. He wants something better for his life, but is unsure what.

Life is beginning to get on top of Reggie as he begins dictating abusive letters. Perhaps he needs a nice peaceful holiday. Unfortunately, his daughter Linda asks him to take her and her family to a safari park, as her husband Tom has crashed their car. Being cooped up in a hot car in a safari park is too much for Reggie, who gets out for a walk and has to be rescued from the lions.

Elizabeth has gone to stay with her sick mother so Reggie seizes the opportunity for some afternoon delight with his glamourous secretary Joan, who proves to be up for it. Sadly, just as they're about to unleash their passions, Reggie is visited, first by his layabout son, resting actor Mark, and then by Elizabeth's right-wing, scrounging brother Jimmy, seeking food.

Still at her mother's, Elizabeth rings Reggie to remind him that she planned a dinner party but Reggie doesn't cancel. Instead he asks C.J. and his wife, young colleague David who toadies to C.J., the well-endowed Davina from the custards department and his rude uncle Percy, who makes sexist comments about Davina.

A nervous Reggie is to address the British Fruit Association and mixes Dutch courage with sedatives, resulting in a disaster and he has to be dragged off. Now at his breaking point, Reggie tells C.J. that blood will flow.

Reggie tries out various new identities, including Lord Amherst (which attracts the attention of the comely Jean) and Donald Potts (which attracts the less comely Miss Pershore). However, he misses Elizabeth and is upset to find that, since she assumes that Reggie is dead, she's seeing an old flame.

Under the alias Martin Wellbourne, an alleged friend of the deceased newly arrived from Brazil, and sporting a curly beard, Reggie gate-crashes his own memorial service where a vague vicar plugs Mark's new play and people seem to miss Reggie less than he'd hoped.