Chan goes to Paris for a reunion with friends from World War I. There he investigates the murder of a munitions manufacturer who was supplying arms to the enemy. At the end Charlie preaches to us about the dangers of peace conferences.

In Puerto Rico to investigate a glut of contraband diamonds that are flooding the world's jewel market, Mr. Moto and his sidekick, a wrestler, find themselves involved in murders by thrown daggers, the frame-up of an overstressed Army colonel, and a pirate gang led by an unknown boss who has inside knowledge of the ensuing investigation.

In order to win back his girlfriend, Mike Shayne promises to give up his detective practice and get a job as riveter in an aircraft plant. He quickly finds himself investigating the theft of industrial diamonds from the plant's safe and, utilizing a variety of false identities, traces them first to a dress factory and later to a Hawaii...

Lloyd Nolan is back as detective Michael Shayne who's in search of a stolen coin.

Police sergeants Johnson and McManus take on Los Angeles confidence tricksters. Con man Tony Wells, lining up rich widow Jessica Royce as his latest mark, sets up a false paranormal society with other charlatans to convince the credulous Jessica that her late son is speaking to her through their sham seances. When the plan leads to mur...