Porky purchases a new home from a real estate agent, a Gothic-style dwelling that immediately feels eerie. The Cat Lucky is clearly rattled by the creaky corners and shadowy corridors, but Porky insists the place is quaint and peaceful, eagerly looking forward to his first night there.
The moment Porky spots a bat, Sylvester the cat clings to him in fright, slipping under Porky’s coat. Porky shrugs it off, insisting the bat is harmless and announcing he’s going upstairs to bed, while Sylvester should sleep in the kitchen. Unknown to Porky, Sylvester stubbornly follows him all the way to the bedroom, and into the bed itself. When Porky discovers the feline lodger, he kicks him down the stairs and orders him to stay in the kitchen.
Downstairs, Sylvester witnesses a terrifying scene: the house is overrun with murderous mice who are carting off the previous owners’ cat to be decapitated by a hooded mouse wielding an executioner’s ax. Panicked, Sylvester heads back upstairs and hides in Porky’s nightshirt. He attempts to explain what happened in a mime, but Porky dismisses the “ridiculous acting” and insists Sylvester must return to the kitchen. Too frightened to comply, Sylvester pulls a gun from a dresser and contemplates shooting himself rather than facing the mice. Horrified, Porky disarms him and is forced to let him share the bed in order to ease his nerves.
As Porky and Sylvester drift toward sleep, the danger intensifies. Four mice push the bed out of the window, where it becomes wedged on a pole. Half-asleep, Porky asks Sylvester to close the window, but Sylvester, barely awake and walking on air, closes a tiny curtain on a birdhouse, then returns to the bed that no longer exists and falls to the floor. He staggers into the doorway with a large lump on his head. At that moment, he sees the mice preparing to drop an anvil on Porky from a crawlspace above the bed. Sylvester lunges to grab the anvil at the last moment, and Porky wakes to find Sylvester poised over him with it in his hands. Porky questions Sylvester’s intentions, then drops the anvil on the cat’s head and leads the way back to the kitchen.
Descending the stairs, Sylvester notes a hooded mouse rolling a bowling ball down the banister toward Porky—who has reached the bottom. Sylvester rushes down, shoving Porky out of the way just in time, sending the pig headfirst into a laundry basket. The chaos continues as Sylvester, knocked out at the base of the stairs, is flattened by the bowling ball intended for Porky.
Porky storms back from the kitchen, unaware that the basket with Sylvester has disappeared below the floor. He demands to know why Sylvester pushed him, suspecting a sympathy ploy. Over the next scenes, as Porky maneuvers through a gauntlet of tools and weapons wielded by the unseen mice, Sylvester remains unconscious in the basket, lowered below the floor and then raised again around 4:00 a.m., his normally black fur now pale gray. Traumatized, Sylvester makes his way to Porky’s room, startling the pig with his frightening pale appearance.
Desperation leads Porky to drag Sylvester downstairs and show him there is nothing to fear. In a tense moment of quiet, Sylvester peers into the kitchen and sees the mice parading as before, except now Porky is bound and gagged, slated for decapitation. The mice haul Porky away, and a tearful Porky holds up a sign that reads “YOU WERE RIGHT – SYLVESTER.” Sylvester is horrified and bolts from the scene, fleeing into the night.
As he catches his breath outside, Sylvester’s conscience—a miniature version of himself wearing a wizard’s robe and carrying a star-tipped wand—appears with an easel. The conscience scolds him for abandoning Porky to danger, reminding him of how Porky raised him from a kitten and showing the stark size difference between a cat and a mouse. It urges him to return to the house and take action. Rejuvenated, Sylvester grabs a makeshift weapon, first a branch and then an entire tree, and charges back into the mouse-infested house to fight. He drives the hundreds of murderous mice into retreat, much to the delight of his conscience.
With the mice seemingly defeated, Porky thanks Sylvester for saving his life and offers a gracious apology. But a final threat remains: a single leftover hooded mouse emerges from a longcase clock, wielding a large wooden mallet. The mouse, who then reveals himself as a Lew Lehr caricature wearing a Napoleonic-era bicorne, chuckles and delivers the final quip: "Pussycats is the cwaziest peoples!"
