This was a fun enough little book, albeit a bit silly and not all that believable. On the other hand, I can see that Hollywood could have had a wonderful time dramatizing the book, what with car chases and people climbing around inside chimney flues and also having fights inside the flues and on the roofs and so forth. But, as nearly as I can tell, no movie has ever been made.
The book begins in Cambridge where one of the dons appears to have been murdered along with an undergraduate who has no known connection to the don. Inspector Buller tries to ferret out the scoundrel, and thinks he knows "who dunnit", but can't prove it. He talks to the murderer, who has since also murdered one of the college porters (door keeper to us Yanks). The murderer confesses, but since there is zero tangible evidence against the murderer, he can't be arrested and tried. Buller is despondent and quits the police force.
A few months later, Buller visits his friend Charles Darcy at Pemberly. Darcy lives there with his sister Elizabeth. Yes, they are of the lineage of the original Fitzwilliam Darcy and Elizabeth Bennet from Jane Austen, and it's allegedly the same Pemberly. That's about all the Jane Austenism one gets, however. Just the use of some names to provide some flack to intrigue the reading masses and con then into buying this unremarkable book.
Anyway, Buller tells his tale to Charles and Elizabeth (btw, he's madly in love with Elizabeth, but since he's a lowly policeman and she's a baronet's daughter, he figures there's no hope and mostly pines away in vain). Charles is incensed for some reason and goes to Cambridge to tell the murderer that he, Charles, is going to get the guy. So, the guy laughs at Charles and tells him to watch his own back. Then for much of the rest of the book, the murderer haunts Pemberly by living inside the chimney-flue system and sneaking into people's rooms at night, leaving frivolous, but tangible evidence of his sneaking, so as to scare them, and have a bit of fun for himself. He's got a huge ego, which is partly justified because he is actually rather brilliant. No surprise about the brilliance, of course: he is a chemist, after all.
Anyway we have lots of adventures and eventually come to a conclusion. T.H. White is a rather famous author, but certainly not for this book.