The mystery itself is all "haunted" mansions and secret passages and smuggling gangs--nothing groundbreaking, but the character interactions are strong and the dialog is witty and the whole thing is just fun, even if the adventure takes a little while to kick properly into gear. A good book to read while on vacation and feeling frivolous.
The 2017 movie version of Crooked House, on the other hand, is very much not frivlous. The Agatha Christie novel is her usual bend of puzzle and character study, though a bit darker in tone than many of her works. The movie adaptation, on the other hand, was clearly taking its cue from the noir film genre, complete with the femme fatale and a private eye with a complicated relationship with the police. It's beautifully shot, and there are some very strong performances, and the ending is a bit like a gut-shot. Given the subject matter it's not exactly an easy watch, but it's definitelly engaging, and well-paced. It's definitely not the book, but stands well enough on its own that I don't begrudge it the changes to characters and plot.