The Killer Paid in Cash: a murder mystery puzzle book.

Part One is the register, printed in full. Each line gives a folio number, the guest's name, the day they arrived, the desk's time stamp, the room and how the bill was paid. After it come 20 clues, built from what the staff remember. Work through them in order, striking out each folio a clue rules out. When the last clue is done, one folio is left.

Part Two is the case file: the evening clerk's statement and the bar manager's, a housekeeping sheet, the front desk book, the switchboard log, the lounge program and a letter from Arthur's desk. Once you have the false name, these tell you which of 4 suspects used it, how they got through a door that locks itself, and why.

Help comes a little at a time, so you read only what you need. Checkpoints printed upside down give the count after clues 6, 12 and 17. Every clue has 3 hints. A table of check numbers tells you whether your folio is the right one, and if it is not, which clue to read again. The full solution is sealed at the back.

There is help online too. The free answer check, which the book prints as riddleportal.com/paid-in-cash, checks your folio and then your 3 answers from Part Two, one at a time, with 3 hints for each.