Why would someone want a clock that screams? In the ninth adventure in Robert Arthur's classic mystery series, the Three Investigators have to find out. The answer could help Jupiter, Pete, and Bob free a man who's been wrongfully imprisoned - and time is running out! Who was the mysterious A. Clock? What does the trail of clues he left behind him mean? And how will a book cipher and a room full of clocks lead to the twisted truth behind this complex and exciting case?