There's a Hamster in My Pocket! — Franzeska G. Ewart

Yosser's having a worrying summer. Her family's shop is struggling and Auntie Shabnam is coming to stay to sort things out. Which means Yosser has to share a room with Nani! And while Yosser is desperately jealous of all her friend Kylie's pets, Kylie's family are not without problems either. Her mum is about to turn 40 and her big brother Sniper is behaving very suspiciously indeed.
And when Yosser discovers a mysterious box among Nani's things, she begins to suspect that it is at the root of all the bad luck. Can Yosser and Kylie get to the bottom of Sniper's strange behaviour, find the perfect present for Kylie's mum, solve the mystery of the locked wooden box and all without losing Kylie's hamsters?