Quarantine in the Grand Hotel centers around a mysterious murder in a hotel on the island of Little Lagonda, which is put under quarantine because one of the guests seems to have contracted bubonic plague. However, just before the quarantine is declared, the police arrive, and so does a young man, who hides in his pyjamas in the wardrobe of Miss Maud Borckman. It turns out that of the numerous guests under quarantine, any number could have committed the murder the police have come to investigate, including the stranger in pyjamas and Maud, as well as a prince and a janitor, even a police officer. Hilarious mayhem abounds all around as the true identities of the hotel guests come to light, and the stranger in pyjamas finally gets to take a hot bath and lays hold of some clothes.