Plot: Silver, who once worked with Lupin on a train robbery, stole the money himself, hid it somewhere, and promptly got himself thrown into prison on a rinky-dink charge. Lupin, having learned that Silver is about to be released, goes to the prison intent on making Silver tell what he did with the loot, only to discover that, while Silver was in prison, a new top-of-the-line prison was built over the site where he hid the money