The Underground Affair is one in a series of three Spy Kids Learning
Adventures games. In this episode, a huge amount of anti-gravity mineral ore
has gone missing from its silo. This material has applications in the spy
business and the Spy Kids are called in to investigate the situation. In order
to solve the mystery, the Spy Kids must solve a series of puzzles in an
accompanying book. The action unfolds in a colorful, comic book-style of
narration.