It is one of approximately eight billion works of fiction inspired by The Strange Case of Dr. Jekyll and Mr. Hyde. After the morning milk is delivered, Tom sneaks out and steals a bottle off the front porch. He pours it into a bowl to drink but Jerry gets a straw and starts drinking as well. After Tom's increasingly frantic attempts to stop Jerry from drinking the milk fail, he resolves on murder. He dumps all sorts of poisons from the closet into the milk and sets it out for Jerry to drink.
Unfortunately for Tom that decision backfires. The milk doesn't kill Jerry; instead it turns him into a super-mouse, three times bigger and super-strong. This new Mighty Mouse version of Jerry promptly turns the tables on Tom.
- Chased Off into the Sunset: Ends with Jerry chasing an ant-sized Tom around the house.
- Cranial Eruption: Predictably, Tom's attempt to whack Jerry with a club when Jerry is on top of his head leads to Tom raising a lump on his own head.
- Eye Pop: Six pairs of Tom's eyes project out in front of him when he sees Jerry still sipping out of the bowl of milk after Tom has locked him in a trunk.
- The Hunter Becomes the Hunted: This happens every time Jerry turns into the super-mouse and chases Tom. And again at the end, after Tom's drinking the poisoned milk causes him to shrink to the size of an ant.
- Impact Silhouette: Tom's attempts to whack Jerry with the fireplace poker do nothing but leave Jerry-shaped bends in the poker.
- Metronomic Man Mashing: Jerry slings Tom around in this manner after getting super-strength.
- Miraculous Malfunction:
- Tom dumps a bunch of gunk in the milk—acid, ammonia, moth balls—but instead of making the milk poisonous and killing Jerry, he creates an enlarging potion that gives Jerry super-strength.
- Then at the end Jerry frantically tries to recreate the potion as Tom is chasing him. Tom, triumphant, grabs the saucer of poisoned milk and drinks it. However, instead of turning into super-Tom he shrinks to the size of an ant. The cartoon ends with Jerry chasing him with a fly swatter.
- Murder Is the Best Solution: After Tom fails to stop Jerry from drinking the milk, he shuts himself up in the closet with the bowl. Instead of drinking the milk in peace, he decides to poison it and leave it out for Jerry.
- No-Sell: Nothing Tom does to stop Jerry has any effect at all. Nothing. Tom attempts to whack Jerry with a book. The book breaks on Jerry's head and he tears it in half, then tears the other half into quarters. Tom whacks Jerry with a poker four times. All this results in is four mouse-shaped dents in the poker. He shuts the living room door and holds it shut. Jerry simply walks into the door and it falls down around Tom. Truly terrified by now, Tom barricades himself in the wall safe. Jerry drills through it with his fist and pulls Tom out through the hole before slamming him against the safe numerous times. Only then does the concoction wear off.
- Super Serum: The accidental magic milk potion, which turns Jerry into a super-mouse.