Thought I'd do one of these for once.
Recently completed: The Sleeping Sphinx by John Dickson Carr
This is the second one of Carr's books I've read where the aim seems to be breathlessness: the protagonist is thrown into the plot without being given any chance to stop and think, he has to react to events as they occur, and any time Dr Fell tries to explain what's going on, he's called away or suspects burst into the gathering demanding instant attention.
(The other one like that was Till Death Do Us Part).
It stands up quite well for the most part, though I think a mental health professional might have something to say about its handling of 'hysteria' in women.
Previously: Sir John Magill's Last Journey by Freeman Wills Crofts (re-read)
By way of a complete contrast: Crofts' detectives like to take things slowly, and carefully, and come to a halt now and then to sum things up for the reader. This one is set in the same part of the world as Dorothy L. Sayers' Five Red Herrings, and was published shortly before it; consequently, it gets a shout-out in 5RH, and that's how I first heard of it. Like a number of Crofts' books, it's a fair-play mystery, provided that you've got maps of Galloway and Northern Ireland and the sea between, and are willing to work out exactly who was where at what time and how fast they could travel.