June McCarthy has unwittingly aided an undercover Nazi naval officer with acquiring a "mother ship" for German submarines in the Atlantic.

In 1915 France, Major Brand commands the 39th Squadron of the Royal Flying Corps. The young airmen go up in bullet-riddled "crates" and the casualty rate is appalling, but Brand can't make the "brass hats" at headquarters see reason. Insubordinate air ace Captain Courtney is another thorn in Brand's side...but finds the smile wiped from his face when he rises to command the squadron himself. Everyone keeps a stiff upper lip.

Dr. Paul Carruthers is frustrated because he thinks his employers, Mary Heath and Henry Morton, have cheated him out of the company's profits. He decides to get revenge by altering bats to grow twice their normal size and training them to attack when they smell a perfume of his own making. He mixes the perfume into a lotion, which he offers as a gift to Mary and Henry. When they turn up dead, a newspaper reporter decides to investigate.

Paul Kriza is a cashier of a bank in a small town, and the happy husband of Anna and the father of four children. He is sent to New York to deliver some securities for the bank. There, he is tagged as easy-pickings by a con-game gang and Mary Brown, gang accomplice, proves he is. Waking up in the morning he discovers he has been robbed of the securities and, when he confronts the gang, he is hit on the head and taken out to be left on a railroad track. He comes to, struggles with the henchman and the man is killed when a train comes roaring by. Paul escapes but his watch is found and he is reported as the dead man. But he can't go home again.

Victor Ballard, a happy-go-lucky albeit impoverished sidewalk photographer, shares a New York City studio apartment with Polish immigrant painter Stefan Janowski. The big city doles out joy and misery indiscriminately: In the apartment below Victor and Steve, Gus Nelson learns that his wife has given birth to quintuplets, while the lonely tenant in the apartment below Gus has given up on life and committed suicide.