Watch Zero the Hero for Free: How to Stream the Movie Online at 123Movies. . Zero the Dog, already a failure as a bloodhound or a retriever, is just as bad as a watchdog, and is frightened when a burglar appears. Casper the Friendly Ghost, unknown to Zero, comes to his aid and frightens the burglar away. Zero thinks he did it on his own, and gains back all of his lost self-respect.