Mary Marvel #17 (1947)

Mary Batson goes to visit Uncle Dudley at Shazam, Inc., but finds that business is lofty lately. A rich woman named Mrs. Upcreek begs for their help finding her dog, Brutus, and gives Uncle Dudley a written description. He promises the dog will be back in 24 hours and Mary finds the description went out the window by accident. Uncle Dudley presumes that with a name like “Brutus,” he's likely a big dog and changes into Uncle Marvel to go to the dog pound. He accidentally leaves a door open and the dogs run out, forcing Mary to call SHAZAM to become Mary Marvel and gather them up quickly. They decide to see if he's been reported found in the paper and they find that kidnappers are demanding $10,000 ransom. Uncle Marvel goes to deliver the ransom, but reveals that it's fake money and tries to cross up with him, but he merely throws the money in Uncle Marvel's face while his goon, Mike, kicks him in the tailbone. Mary hears him and calls SHAZAM and becomes Mary Marvel, punching them off of him and Mike and his boss, “Barky” Bowzer. They manage to wrangle the dog, who leads them to Barky's hideout. Uncle Marvel grabs one of their guns and holds the goons up, but Barky calls in his other attack dog, Rex, who bites him in the rear. Mary Marvel charges in to find that they're all laughing at Uncle Marvel, who is hanging from a light fixture on the ceiling. They defeat the goons quickly and find Brutus was locked in a closet and satiate the attack dogs with some meat in the fridge. They're soon arrested and go to deliver Brutus back to his owner. Unfortunately, they find that this isn't Brutus, but a neighbor's dog named Bonzo who also went missing. Suddenly, a tiny Chihuahua leaps out of a fruit bowl and bites Uncle Marvel on the hand, revealing that Brutus was hiding in her house all along!