Tired of Punkin's constant attempts to nail him, Mushmouse summons his family, who confuse Punkin' because of their lookalike appearances.
Mushmouse mixes an enlarging draught which does the opposite of its intended purpose. Punkin' accidentally drinks the draught and faces a difficult fight with Mushmouse, followed by a shrunken hound dog.
Mushmouse helps a hound dog from a sticky situation and in return he offers to come and help Mushmouse with Punkin'. In response, Punkin' gets his own ally, a skunk called Stanky.
Mushmouse is in despair, when his cousin Megaton Mouse comes by. Megaton drives Punkin' mad with a lookalike appearance to Mushmouse but unbelievable strength.
A stranded Lion is invited by Mushmouse to stay with him and Mushmouse keeps him out of Punkin' and Harmony Sue's sight. The Lion beats Punkin' eventually forcing him out of the house.
After several close shaves from Punkin', Mushmouse leads the US Army to intimidate Punkin' to the point of surrendering.
Punkin' takes Mushmouse to the Hog Wallow Research Institute for some cash. An experiment turns Mushmouse invisible, giving him a tremendous advantage over Punkin' until it wears off.
Mushmouse is going courting. Mushmouse, determined to please Hunnybun, confronts Punkin'. All that keeps Mushmouse going is Hunnybun's incentive kiss until Mushmouse finds his girlfriend after his favours.
Punkin' and his new neighbour Tennessee Tabby fight over who gets to pin down Mushmouse. Mushmouse sneakily tips the two cats with methods on getting at each other until they find out they've been duped.
Mushmouse receives a package containing a remote controlled mechanical watchdog. After assembling it, Mushmouse names it Chomper. Punkin's efforts against the Chomper are futile even when he blows it up.
A female cat spends the day chasing Punkin Puss because she's in love with him.
Mushmouses' attempts to beat Punkin' with fitness don't work, so he orders a boxing kangaroo named Hunka Hunka. Punkin' mistakes Hunka Hunka for a very fit Mushmouse and fails every time to beat him.
Mushmouse gets chased by Punkin' to a sleeping bear, who doesn't like to be disturbed. Mushmouse gets Punkin' repeatedly in a punch up with the bear, until he gets annoyed and keeps Punkin' tied up.
Mushmouse's cousin Bat Mouseterson arrives for a visit. Mouseterson hits Punkin' for every rude action he resorts to. When Mouseterson has to leave, Mushmouse has to fend for himself.
Mushmouse tries to contact Super Duper Duper Duper Duper Duper Cat (or Super Duper Duper Etcetera Cat) in hope he'll save him from Punkin'. Punkin' impersonates the superhero until the real one comes to Mushmouses' rescue, but has to leave for Hollywood.
Mushmouse is about to give up his life of feuding, when a package containing Speedo pills arrives. Those give Mushmouse a great advantage over Punkin'. When Punkin' discovers them, he takes an overdose.
Mushmouse answers an ad in an attempt to escape Punkin' Puss. He leaves and heads to Beverly Hills, but the posh living environment that he hoped for comes with strings attached. He lives with a mild-mannered rich cat who kind of abuses him in a different way.
Mushmouse orders a Mouse From S.O.M.P. Kit, so he can defend himself from Punkin'. Punkin' gets a similar kit to counter Mushmouse getting them evenly matched.
After Mushmouse gets Punkin' knocked out in a feud, he tricks him into thinking he's become a ghost. Mushmouse proceeds to get Punkin' to spoil him, until Punkin' see's through his trick.
Punkin' Puss gets a knockout, dreaming of the Feudal Age with Saxon mice and their king Mushmouse. Punkin' is faced with Meany Mouse and eventually wakes up from this dream and resumes feuding with Mushmouse.
Mushmouse inherits from his late uncle ₤1000. Punkin' treats Mushmouse better in hope of getting a share. To their surprise the inheritance is one thousand pounds of cheese.
Mushmouse mixes a potion similar to Dr. Jekyl's formula, which turns him into a monstrous mouse. When Punkin' tries it, he unleashes a mean doppelganger of himself.
According to Mushmouse's horoscope book, today is Punkin's unlucky day. Sure enough Punkin' encounters many misfortunes until the next day, which is Mushmouse's turn to face misfortune.
