Sylvester the cat lives in the Slobovian Mountains. He chases a mouse with East European music played in the background, and explosives. He tries to catch him and ends crashing into the mouse hole door turning him into a lid. With the mouse staying in his mouse hole. Sylvester leaves a cheese in the floor and winds its scent to the mouse hole. The mouse steps out the door and his eye pop out of his face at what he sees and gets it. While distracted Sylvester changes the door lock with another door lock and hides. The mouse notices his door locked and tries to open it with his keys as Sylvester approaches him with the key which can unlock the door and eats it. The mouse grabs a giant mallet and hits Sylvester's foot, making him open his mouth and stick out his tongue, which has the key on it. The mouse grabs the key and unlocks his door and ducks inside, momentarily coming back out to grab his cheese. Sylvester then makes a female puppet with his hand. The mouse sees "her" and begins dancing with "her". Sylvester then attempts to hit him with a mallet. The mouse notices him and commands him to stop and drags the puppet into his mouse hole leaving Sylvester confused. The mouse then discovers the puppet was Sylvester's hand and changes its disguise to look like him. Sylvester notices the mouse puppet coming out and hits it with his mallet and ends up hitting his own hand before chasing the mouse who hides in one of the desk drawers. As Sylvester searches the drawer, the mouse climbs up to the upper shelf. The mouse then notices a small bottle of nitroglycerin. Getting an idea, he empties it in a bowl and refills it with water. He then gets Sylvester's attention by tossing the bottle in his hand, causing Sylvester to panic and hide inside the drawer. Unbeknownst to the mouse, he inadvertently tosses the bottle of water onto a shelf and a bottle of real nitroglycerin lands on his hand, which he continues to toss. When Sylvester sticks his head out, the mouse drinks the nitroglycerin, still thinking it's just water, freaking Sylvester out. The mouse then jumps off the shelf like he's deliberately trying to cause an explosion, and Sylvester catches him on a pillow before lecturing him. The mouse then hits him square in the head with a fireplace poker and a lump forms on top of his head and pops out of his hat. Angrily, Sylvester grabs the fireplace poker and tries to hit the mouse but stops at the last second when he realizes he'll cause an explosion. The mouse then sticks a cigarette in his mouth and lights it. Panicking, Sylvester takes the cigarette and repeatedly stomps on it whilst the mouse sneaks away. The mouse then dives from the ceiling rafters. Sylvester quickly grabs a baseball glove from a trunk and catches him before passing out. Awhile later, the mouse hauls a large safe up over him. Sylvester then wakes up and sees him let go of the rope and allow the safe to fall straight down on him, forcing Sylvester to take the hit to prevent the mouse from exploding. Having had enough, Sylvester grabs for the mouse, but he starts jumping, scaring Sylvester. The mouse then starts Russian dancing as Sylvester backs into a corner in panic. Unaware of the danger of actually exploding, the mouse dances wildly before he final explodes, leaving behind a wisp of smoke, and a smudge on the floor. The mouse's spirit then finds himself ascending to Heaven, much to his surprise. After seeing where he is, he merely shrugs. Back at the house, Sylvester is still looking at the spot where the mouse exploded when the narrator speaks to him, laughing as he tells him he'll never catch the mouse now. Sylvester (in his only line of dialogue) then mocks the narrator's laugh and says; "Nya-ha-ha-ha-ha! That's what you think! Ah-ha-ha-ha-ha!" He then heads to the shelf and grabs another bottle of nitroglycerin and drinks it before jumping and Russian dancing until he explodes. Floating on a cloud wearing angel wings, the mouse looks on smiling that he's safe. That is, until Sylvester, also wearing wings, appears beside him, much to his shock. Sylvester then chases the mouse around the clouds.
This was the first cartoon to be reissued in the Blue Ribbon Merrie Melodies series with the original credits intact. This was also the first to continue the original ending trend until the 1959-64 season, when most of the cartoons reissued during that period used the reissue ending cards.