Duncan joins doctor Diana - whom he has helped by lancing a patient's boil very roughly - in protesting against the hospital swimming pool being demolished to make way for a new wing. Sir Geoffrey promises to keep the pool but goes back on his word and Duncan, Diana and other protesters lie down in front of the bulldozer coming to get rid of the pool. The driver is none other than the man with the boil and the bulldozer ends up demolishing Sir Geoffrey's car.

Sir Geoffrey and his wife are visiting her mother and he asks Duncan to look after his cat, Thomas, which wees everywhere and is not good-natured. Thomas gets put with the lab animals and Duncan assumes he has been taken away for experimentation. He buys a replacement cat but Sir Geoffrey claims this is not his Thomas. Thomas is saved, making Sir Geoffrey think again about animal tests, but, oddly, gives birth to kittens. Lady Loftus explains that the first Thomas died and she replaced him behind her husband's back, unaware that this cat was a different sex.