the Mystery of Talking Skull in Bloomington, MN

At the beginning of Robert Arthur's tenth and final novel in his classic mystery series, Jupiter Jones buys an old steamer trunk at an auction. The trunk originally belonged to a magician who has gone missing and contains a skull named Socrates, which is reputed to talk. But the boys soon discover that others want the trunk, too - including Three-Finger Munger, Maximilian the Mystic, and a mysterious woman named Zelda. Does the trunk hold the clue to the Great Gulliver and the money that has gone missing? What does Socrates have to say about that?