I've been reading The Finishing Stroke by Ellery Queen, and goodness, it's got some lovely, unnerving moments.
Twelve people are invited to a huge old house for two weeks over Christmas. On Christmas Day, someone dressed as Santa pops into the living room to distribute gifts, and they're all so busy unwrapping them that they don't ask at first - if all 12 of them are in the room, then who was Santa?
This is the best part. A glance at the unbroken snow outside tells them that not only is the intruder still in the house, but that he's been there since before the snow stopped falling the night before. They search the house, but it's so big and has so many rooms and stairs that Santa can keep ahead of them if he wants. They find nothing.
So they've been there for three days now, all the time knowing that there's an intruder in the house with them, delivering odd, cryptic messages and gifts to the host every evening and prowling about as they sleep. Brr.
But then the host starts behaving strangely - popping up in what seems to be almost two places at once, not remembering events that took place the previous day. This would be pretty effective, I guess - if not for the fact that we learned IN THE VERY FIRST CHAPTER that the host has a twin brother from whom he was separated at birth. Guess we figured out who the 13th guest is.
Remember A Study in Scarlet, the first Sherlock Holmes novel? Remember how they caught their man, and then a new chapter began explaining the backstory, which took place decades ago on another continent? Maybe Dannay and Lee should have held off on revealing the secret twin until a more dramatically opportune moment.
I'm still looking forward to seeing what the sandalwood ox gift has to do with it, though.
UPDATE. It appears I owe Messrs. Dannay and Lee an apology. The plot has thickened, and the twin doesn't figure. (Or does he?) I'm enjoying this so much more than Calamity Town!