Tom Swift In The Land of Wonders, or, The Underground Search For the Idol of Gold, is Volume 20 in the original Tom Swift novel series published by Grosset & Dunlap.

Envy, rather than fame or fortune, drive Tom to finally accompany the expedition to Honduras, as Tom hopes to prevent Professor Beecher from discovering the idol and presenting some of the gold to Mary Nestor as a betrothal gift.

Prior to Professor Bumper's arrival, Tom Swift is working on a new gyroscope, which was also briefly introduced in the previous volume.

In Europe, World War I continues to rage, and several European governments have expressed an interest in Tom Swift's new gyroscope, as safety devices for use in the aerial aspect of the war.

When envy drives Tom to join the expedition, Tom hands the gyroscope project over to his father, Barton Swift, and it is not heard of for the rest of the story.