Author of detective novels, Priscilla Pringle, is pleased to find that she is sharing a railway compartment with a gentleman who happens to be reading one of her books – Murder in the Cathedral. He is military officer, Captain Bulkington, who recognises Miss Pringle and offers her œ500 to collaborate on a detective novel. To everyone's surprise, Miss Pringle is rather taken with Captain Bulkington – is she out of her depth?