You spot a two-letter word that starts with the free T. It has to be TO. You fill in the O, and suddenly an eight-letter word reads T _ _ O _ _ _ _ and your brain refuses to let it go. Five minutes later you’re muttering at a 135-year-old sentence about evidence. That’s the cryptogram …

You see SCARLET, MUSTARD, PLUM and BLUE, and you’re already reaching for the Submit button. Four colours, done. Except PEACOCK is sitting two tiles over, smirking. Now you have five candidates for four slots, one mistake on the board, and a creeping suspicion that this puzzle was written by …

The front door booms shut behind you and a bolt slides home on the far side. You didn’t hear anyone follow you up the drive. Somewhere down the hall is a dead man, a locked desk and three people who all have a very good reason to be somewhere else. The coachman is clear about it: nobody leaves …