Dr. Simon Sparrow's (Sir Dirk Bogarde's) love life improves dramatically when the lovely Delia Mallory (Samantha Eggar) is brought into casualty with a sprained ankle. She's relieved at the diagnosis, as she is a model, and is as attracted to Sparrow as he is to her. Sparrow finds himself treating Sir Lancelot Spratt (James Robertson Justice), who has taken to sleep-walking. He has also quite suddenly lost his gruff manner, and is being quite nice to everyone. Sparrow quickly diagnoses Spratt's condition: he's fallen in love. The object of his affection is Physiotherapist Iris Merchant (Barbara Murray). Sparrow urges him on, but she also has another suitor in the form of Major Tommy Ffrench (Donald Houston). Spratt tries to hire a private detective to follow her, but when that doesn't work out, he takes to following her.