The Patient in Room 18 (1938)

Patric Knowles is noted author and crime specialist Lance O'Leary. He has been acting strangely after failing to solve a case and winds up in the hospital with a nervous breakdown. The doctor prescribes him rest and an absolute ban on anything to do with crime solving. Ann Sheridan is nurse Sara Keate, who tends to Lance and runs the hospital ward. Nurse Keate is Lance's girlfriend, is currently mad at him, and turns out to have an investigative streak of her own.

The setup is definitely comedy, and while the plot involves murder and missing radium, the emphasis is mostly on laughs in this modestly entertaining B mystery.

A rich patient has just bought the hospital $100,000 worth of radium and then checked right in. They put him in room 18 and he goes off to sleep with the radium taped to his chest. (Yes, taped to his chest--partly to safeguard the radium but mainly for the excellent health benefits.) Almost immediately the patient is murdered by a shadowy figure; the radium disappears. Who did it?

Among the suspects are a lawyer, a doctor, and various other characters who sneak around the hospital acting suspiciously. The police are called in, of course, but they seem perfectly happy to let Lance work on the case, while Nurse Keate gathers clues as well.

The plot really isn't much but Knowles and Sheridan are fun to watch. Knowles's best trick is hiding a lit cigarette in his mouth--until Sheridan catches him at it. Like that old trick, this movie is nothing particularly original but plenty enjoyable nevertheless.