Boy Detective #4

Boy Detective Dan Taylor faces a homicidal maniac who laughs while committing murders in a skyscraper. The killer traps Dan and a woman in a room where a brick wall slowly descends to crush them, but Dan jams the mechanism and saves them both. In a separate story, Pete Dowell, a criminal who read crime-doesn't-pay reports, moves to the country and gets a job training, but then targets a wealthy couple's emerald collection at a party, planning to rob them at a shabby hotel hideout.