A mastermind is building a hidden crossword. The detectives have to read it.
The mastermind plays a word face down each round, scores it, and hands over a clue sheet: how long the word is, and what it scored.
The detectives get one guess a round. Right letter, right place gets a box; right letter, wrong place gets a line.
Crack a word and its points move from the mastermind to you — and its tiles turn face up, which gives away letters in everything that crosses it.
First past the target ends the round, and the higher score wins: escape, or conviction.