“This story is dedicated, as it should be, to fellow-passengers aboard M.V. GEORGIC, in memory of a crossing we made from New York to ‘a British port’ during the early days of the war.

The crossing took place under the same black-out and life-jacket conditions as are described here. But there all semblance to reality ceases. The date was September, 1939; not January, 1940. The ship was not carrying munitions. There were no such regrettable goings-on as occur in these pages. No character in the story – whether passenger, officer, or member of the crew – bears the remotest relation to any living person. In short, everything except the atmosphere is a complete fantasy from beginning to end.”

“Should you imagine that Secret Service means a holiday from finger-prints and photography you are mistaken. Such a title as Murder in the Submarine Zone holds out a promise of this only to those who are unaware that Chief Pursers study criminal investigation. When there is a murder aboard the EDWARDIC, crossing the Atlantic with a cargo of explosives, she becomes a floating Scotland Yard with enough enlarged finger-prints to be regarded as additional cargo, and Sir Henry Merrivale has something fresh to tell the ordinary reader about them. War is used here simply as a highly dramatic background for a “who-done-it” that would be puzzling even in peace conditions. In a cold-blooded post-mortem frame of mind, the reader may wonder at the lavish amount of criminology expended on a murder or two, but while the hunt is up the excitement is unfailing. From the start it is fairly plain that a U-boat alarm will be sounded: yet when it does happen the suspense thrills. Likewise the expected news “The Navy is here,” comes like a blessing. With so satisfactory a detective as Merrivale and a criminal made on no ordinary mould, the tales passes all the customary crime tests with honours.”