Suzie fantasizes about going to Mexico City on the next case, untilDan lets her know of the danger that awaits as he has to prevent a murder. Arthur Meade is the man who needs help, and once Dan arrives, the phone call is abruptly cut off. How can Dan locate him? Who might know about the case?
Dan isn’t without clues. He goes to visit a Mr Lucas, who isn’t helpful, and is even a bit evasive. Then he looks for a gal named Marilyn. Dan is only convinced that the two are a set of characters of the same vane.
Back in his room, Dan gets a surprise visitor. Who is it? What are they up to besides nothing good? Dan is only certain that Lucas really doesn’t know what happened to Meade.
There’s a Mexican man who pops up through the story, and suddenly he shows his hand as he threatens Dan with a knife. The man stops short, and demands money from Dan for not killing him. Wondering why the change of events, Dan gets an idea of how to contact Meade.
A meeting is arranged, and a package is to be delivered, and a warning of more danger from Lucas. While awaiting the package, Dan spots Marilyn sneaking around, and eavesdrops on her making plans with a Mexican local to do a poisoning job.
Dan has some ideas of his own as he goes along as the target of the poisoning scheme, and brings in the local cops for backup. In the process, the killers are exposed. And what about Meade? Dan figures out the story behind him as well.