SOLVED. Book about characters that mind transfer into lab rats (potentially YA, from 2000s). [s]

[Jessica]

I purchased a book in the mid 2000s about two main characters. I think they were a man and a woman. They ended up having their minds transferred into lab rats so that they experienced the lives of the rats for short times. There may have been other transfers too. I remember the characters trying to escape the scientist or magician to get free at some point. And there were some disturbing accounts of lab rat welfare issues. It may have been YA or sci-fi/fantasy or just general fiction.

The book had a title like “the incredible story of Mr. P” or “the unbelievable tale of Mr. Q” or something like that. The only other thing I can remember is that the page edges were black. In my memory, the cover looked similar to the original Hugo Cabret cover, but I’m less sure about that. I may have purchased it at a bookshop in London or in the US. I have been trying to figure this out for years. I mistakenly donated the book to a charity thing and then couldn’t remember the right details to repurchase!

[Ayshe]

Maybe The End of Mr. Y?

[Jessica]

Yes! Thank you so much!