A murder in Chinatown where jewels were stolen gains the attention of Philo Vance. The cops have already picked over the crime scene, but Philo seems to already know how to handle the situation to lure out the killer. He is a criminal psychologist, and detective, and has a knack for profiling people.

Philo is aided by a young Chinese man, born in America, and tossing around the slang of the times like a pro. Philo isn’t out to butt heads with the cops, but work with them to hand over the crooks. What makes Philo so sure of himself? He tells his Chinese friend, Lee, all about it. There’s just one problem, traps sprung for bad guys in the first 15 minutes of radio programs are doomed to fail. Crooks don’t get stupid until the second half of the show. Everybody knows that.

The facts emerge like this: the diamond is missing, these crooks were spotted fleeing the scene, but when they’re quickly caught, there’s no diamond. Has Philo’s plan backfired? Though the evidence points to futility, Philo still has ideas that could prove who the bandits really are.

Might there be an accomplice? Philo puts his friend Lee wong to work to try to get the inside scoop of what’s going on with the crooks. The pressure is on, and the crooks are beginning to squirm. It looks like that trap will work now, especially since it’s the second half of the show. It’s about time for the bad guys to fall for it now.