It is Murych the Cat's birthday. The birthday boy's friends Timofei and Vasily arrive to congratulate him. They give him a fishing rod, a can of worms and a knife to clean fish. As an inveterate fisherman, Murych is delighted with his presents. He promises to go and catch a fish at Anichkov Bridge and reveals his dearest secret to his friends: before casting a line you have to spit on the worm a few times.
Musya and Musilda arrive - Murych is very much in love with the latter. Musylda has forgotten her umbrella at home, and she and her friend are almost drenched. Murych calms her and tells her a merry tale about how once he protected himself from the rain using a copper basin. To honour the resourceful birthday boy, Musya and Musilda perform Rossini's Duetto buffo di due gatti ("Cats' Duet").
Murych boasts that he has been able to slip by the angry dog that has hidden behind the fence. Musilda is thrilled by his courage and calls him a hero. But all agree unanimously that the Grandmother is the true heroine: she never scolds, she cooks tasty food and sings songs to the kittens. She is the best on the planet! Murka Barsikovna is meanwhile laying the table, and Vasily the cat brings a huge festive cake: "A cat's birthday is sheer happiness!"