Sylvester is sleeping on the ledge of a tall building. After observing mild-mannered Dr. Jekyll drinking a Mr. Hyde potion, and briefly turning into a monstrous alter ego, Sylvester laughs it off and resumes his sleep. In a dream-like sequence, Sylvester chases some pigeons away after their coos disrupt his nap. He then pursues his prey, Tweety, along the building's ledge. Tweety escapes inside and hides in the Hyde formula. Sylvester demands that Tweety show himself, which he does: he's turned into an ugly, giant bird of prey that - after years of harassment and being chased and with payback on his mind - begins chasing Sylvester!
Sylvester is frantically trying to get the elevator to come up, and he turns and looks down the corner, and Tweety Hyde is ambling along, laughing maniacally. For most of the rest of the cartoon, Tweety frequently switches between his usual, innocent self (which Sylvester chases) and the evil bird-monster (which goes after the cat). After several back-and-forth chases, Sylvester nabs a normal-sized Tweety. Failing to realize the monster bird and his potential meal are one and the same, the cat locks himself in a small kitchen, throws the key out the window and begins to "make that Tweety sandwich I've been dreaming of." But while Sylvester is searching for some ketchup, Tweety changes back into his Hyde-like self and devours his adversary whole. Sylvester frees himself and tries to escape the room as his hunter murderously stalks him down.
Just then, Sylvester awakens from his dream ... only to see a normal-sized Tweety struggling to fly to the ledge of the building. Sylvester is convinced that Tweety poses a giant risk to his well-being and runs through a wall to escape! Two cats observe his action and refer to it as cowardice. Tweety turns to the viewers and agrees.
On ABC's The Bugs Bunny and Tweety Show, Sylvester's line "I'll jump! I've got a choice?" between the parts of him looking down to the street and jumping off the window was cut, as the censors feared it sounded like Sylvester was committing suicide.