While Tom is throwing darts at an apple on Jerry's head à la William Tell (he even throws one between his legs while blindfolded), a telegram arrives. Though it is meant for his owner, Tom reads it himself and discovers that he has been left a million dollars in a will from his owner's eccentric aunt, making him ecstatic. Jerry also reads the letter and gets just as happy as Tom. Tom quickly learns why after Jerry points out that the telegram has a condition that forbids him to ever harm any living animal, especially mice, or else he is likely to lose everything.
The next day, news of Tom's inheritance quickly spreads and he moves into 1 Park Avenue. Although Tom at first enjoys the attention and wealth he is given, Jerry decides to use the telegram's "Even A Mouse" condition against Tom as revenge for tormenting him. He continually follows Tom, despite the cat's best attempts to get rid of him, and proceeds to take advantage of his freedom through various means, including slapping Tom's dickey in his face, assaulting him in his limousine, eating his sundae, and even throwing him out of bed while he tries to sleep.
The next morning, after Jerry steals Tom's bathroom towel, he decides to get rid of Jerry. After a few ideas, Tom eventually decides on hanging a fire exit sign on the window. He strikes a match to start a fire in front of the bathroom door, and Jerry promptly jumps out of the window. The cat cheers before sitting down to enjoy his breakfast, but when he grabs his napkin, however, he uncovers Jerry, who posts the telegram on the table and eats Tom's breakfast. As a final insult, he attacks Tom yet again with the rest of the breakfast material, reminding him that as long as the "Even A Mouse" rule stands, he can do whatever he wants to Tom, then he once again slaps Tom's dickey in his face. This proves to be the final straw: Tom loses his temper, and the shocked Jerry realizes that he has pushed the cat too far. Tom furiously grabs the telegram, and tears it into pieces. Jerry shows "Even A Mouse" proviso but Tom shoves it into Jerry's mouth, literally making and forcing him to eat his words. Jerry swallows it in horror at what is about to happen, as Tom leaps into the air with a loud and insane but justified scream before attacking Jerry by smashing the crockery and breakfast tray on him. After a few seconds, Tom contemplates that he is throwing away his fortune but he is still happy and satisfied, and then continues attacking Jerry as the short concludes.
- This is one of the few shorts where Tom seemingly wins, since he is happy at the end as he attacks Jerry, even though he loses his chance of earning a million dollars from doing so.
- This was the first cartoon where the William Hanna Tom Scream was used for when Tom gets shocked after he sees Jerry in the car. It was one of the screams (recorded by William Hanna) that first debuted in What's Buzzin' Buzzard? (1943).
- Although the smoking in "Texas Tom" has been removed in Boomerang UK airings, the smoking scene in the car in this episode is left intact.