It's Beryl's birthday, and Sandra is planning a surprise party for her. Among her presents she gets a hamster in the post from Robert. Only Beryl hates 'rodents', or at least she does until she finds out that the hamster is pregnant. She also has a massive goldfish bowl, a far too big knitted jumper, and a strange blue hat from Mrs Hutchinson. They then discover that Thingy has gone missing so the race is on to find it.