In the attic of a large house, Tom is busy designing the "perfect" mousetrap; his blueprint details a Rube Goldberg machine designed to catch Jerry, and eventually become a worldwide success. In addition to the elaborate contraption, the blueprint also depicts stick figures of a mouse and a cat. After drawing the cheese and the mouse, tired from a hard day's work, Tom retires to his bed where he dreams of potential success, fame, and fortune.
While Tom sleeps, the stick figure mouse suddenly comes to life, abseils down the drawing board, and enters Jerry's mouse hole to warn him about Tom's plan. Never having seen such a thing before, Jerry is skeptical and refuses to follow the stick mouse. When he is woken up again, stick mouse makes the decision for him, dragging Jerry to the drawing board and blueprint. Just then, the stick figure cat on the blueprint also comes to life; when the two mice pass by the cat, it reveals itself to them.
Promptly, Jerry hands the stick mouse an eraser, who erases the cat's teeth; it grabs a brush and draws a bigger set of teeth on itself before beginning the chase. The stick mouse draws a mouse hole on an empty space of the blueprint, which Jerry safely enters; however, the stick cat catches the stick mouse by its tail and it unravels until it is nothing but legs. Jerry, with the pen and the eraser, walks behind the cat, draws smaller feet on the upper part of its legs, and erases the rest of them, causing the stick cat to fall down. It looks down at its feet while chasing Jerry and discovers its modification (as well as the realization that it can't run as fast as before), and in return, uses its tail as a lasso to retrieve Jerry.
Meanwhile, the stick mouse draws a bow and arrow and fires it at the cat, who pulls the arrow out of its rear and promptly deflates its own torso. The stick mouse runs away and camouflages itself as one of the flowers in a flowerpot on the blueprint; the cat suspects nothing. While the stick cat turned the other way, the stick mouse ladles the stick cat with a fork as one would do to spaghetti, then runs away as it unravels itself.
Both mice jump off the drawing board, with the stick mouse acting as a parachute, while the stick cat jumps down and bounces akin to a pogo stick until it comes face-to-face with a jet of water fired from a soda siphon by the stick mouse. The stick cat disintegrates into white ink, and before anything more than its head can reform, Jerry sucks the cat into an ink pen and empties it into Tom's jar of white ink. The two mice shake hands, but soon hear Tom yawning, about to wake up; quickly, they alter a key measurement on the blueprint, and both mice narrowly return to their original positions before Tom sees them. Tom gets to work building his mousetrap, not noticing anything amiss.
After his trap is completed, Tom hides in anticipation as Jerry emerges from his mouse hole and grabs a piece of cheese which Tom has tied to his creation. This sets off a complicated chain of events which eventually lead the release of a safe which is to flatten the mouse. Tom emerges from his hiding place and prepares Jerry for his demise by giving him a cigarette, but the altered measurement caused the safe to land two feet closer to the mouse hole and the cuckoo bird cuts the rope with a knife - then it falls onto Tom instead of Jerry. The safe door opens, and the cat walks out, now cube-shaped like the safe's interior. Unaware that the altering of the key measurement of the blueprint by the mice was the real cause behind the trap's malfunction, he curses over his failure while leaning on the safe.
- The Tom and Jerry blueprints in this cartoon are later reused in the blueprints of the Tom and Jerry Tales opening.
- The flashback scene of this episode was shown in Shutter Bugged Cat.
- In 2020, the cartoon was restored along with Downhearted Duckling on Amazon Prime.
- The contraption didn’t match the blueprint.
- The contraption had a paper sign, but was never used. Instead it’s a wooden sign.
- When the trap was built not all of the parts are used.