The 'thief' that Josh and Connor find in Grandad's garden is a cat, quite an old cat and a very hungry one. They, along with their mum have moved into Grandad's house because Grandad is going downhill mentally and can't live alone anymore. The boys want to keep the cat they find, and Grandad becomes their willing co-conspirator. In fact, once Leo is established as the family pet, Grandad actually improves. The vet warns them that Leo will not live long, and after a year of the good life with the family, he dies in his sleep on Grandad's lap. There is quite a lot of good discussion about what death means, and though they are sad, they believe that Leo has gone to live with Grandma Florrie. They have a grand funeral, and for awhile Grandad gets worse again. However, on his birthday they give him a new cat, and he is happy. There are hints that Grandad will not always be with them either, and this could be good preparation for children whose grandparents are coming to the end of their lives. The handling of dementia is very realistic. Good black and white illustrations; a short novel.