[Illustration] THE PLYMOUTH EXPRESS AFFAIR “The little gray cells,” so often referred to by the great detective Hercule Poirot, certainly get in their fine-work in this intriguing mystery story by an exceptionally talented writer. By Agatha Christie Alec Simpson, R. N., stepped from the platform at Newton Abbot into a first-class compartment of the Plymouth Express. A porter followed him with a heavy suitcase. He was about to swing it up to the rack, but the young sailor stopped him. “No—leave it on the seat. I’ll put it up later. Here you are.” “Thank you, sir.” The porter, generously tipped, withdrew. Doors banged; a stentorian voice shouted: “Plymouth only. Change for Torquay. Plymouth next stop.” Then a whistle blew, and the train drew slowly out of the station. Lieutenant Simpson had the carriage to himself. The December air was chilly, and he pulled up the window. Then he sniffed vaguely, and frowned. What a smell there was! Reminded him of that time in hospital, and the operation on his leg. Yes, chloroform; that was it! He let the window down again, changing his seat to one with its back to the engine. He pulled a pipe out of his pocket and lit it. For a little time he sat inactive, looking out into the night and smoking. At last he roused himself, and opening the suitcase, took out some papers and magazines, then closed the suitcase again and endeavored to shove it under the opposite seat—without success. Some hidden obstacle resisted it. He shoved harder with rising impatience, but it still stuck out halfway into the carriage. “Why the devil wont it go in?” he muttered, and hauling it out completely, he stooped down and peered under the seat.... A moment later a cry rang out into the night, and the great train came to an unwilling halt in obedience to the imperative jerking of the communication-cord. * * * * * “Mon ami,” said Poirot. “You have, I know, been deeply interested in this mystery of the Plymouth Express. Read this.” I picked up the note he flicked across the table to me. It was brief and to the point. Dear Sir: I shall be obliged if you will call upon me at your earliest convenience. Yours faithfully, Ebenezer Halliday. The connection was not clear to my mind, and I looked inquiringly at Poirot. For answer he took up the newspaper and read aloud: “‘A sensational discovery was made last night. A young naval officer returning to Plymouth found under the seat of his compartment, the body of a woman, stabbed through the heart. The officer at once pulled the communication-cord, and the train was brought to a standstill. The woman who was about thirty years of age, and richly dressed, has not yet been identified.’