Starts off at the US Embassy in Mexico City. Scenery of street makes Mexico city look very nice. Walter Dorn wants to get Charlie Chan to go there regarding secret plans of a Mr Wyans which someone tried to rob twice. It is kind of confusing as to what countries are dealing with who for the plans.
At the airport Chattanooga Brown is Chan's driver. When they land in Mexico City he is with Chan's son Tommy and Charlie Chan. Brown is a cousin of Birmingham Brown. Birmingham is funnier though in other episodes. Chan is waiting for Dorn to pick them up and he is told Dorn is dead.
Walter Dorn is killed at a gathering at Wayan's apartment by a gunshot. There are many people invited there. Insp.Luis Carvero takes Chan there and they did not find anyone with a gun.
Charlie Chan has some doubts' about Inspector Carvero because the Inspector has has a relationship with one of the women where Dorn was killed and Chan thinks he might be biased.
People get shot but no gun visible. Chan has to figure out what is going on. He has figured out the new plan will make a atom bomb more explosive.
So more investigating needed.