The Moving Toyshop by Edmund Crispin

This isn't a book for those who like their crime fiction watertight and co-incidence free. It's the kind of book where you just have to jump in and accept anything that comes along. If you can do that, then I think you'll find it's a really fun read.

Richard Cadogan goes to spend a few days in Oxford. He discovers the corpse of a woman in the upstairs flat of a toyshop. There is someone else in the flat and that someone knocks Cadogan unconscious. When he wakes several hours later he escapes from the flat and goes for the police. However, when he returns with the police, not only is there no corpse, there is also no toyshop! The police dismiss his story a result of his bang on the head. Cadogan then goes to see his friend Gervase Fen, a Professor of Literature at Oxford University. Fen believes his friend's story (I'm not sure I would've) and together they investigate.

I found the character of Gervase Fen very appealing. Probably he would be infuriating in real life, but in the pages of a book his disregard for his responsibilities and his enthusiasm and curiosity are entertaining. I also like that the characters seem to know they're in a book. At one point Cadogan is trying to persuade Fen to go to the police and says;
If there's anything I hate, it's the sort of book in which the characters don't go to the police when they've no earthly reason for not doing so.

There are literary references scattered throughout, for example, the crime centres around an Edward Lear nonsense poem. And one of the chapters is called 'The Episode of the Indignant Janeite' and involves a drunk man who bores Cadogan and Fen to tears with his defence of Jane Austen's novels.

I think this is a light, fun read for when you're in the mood for something not too challenging. It's one of a series, the first of which is called 'The Gilded Fly'.