A good MG historical fiction choice.
Elias is sent to an experimental consumption clinic in Mammoth Cave, Kentucky, in 1843. Chafing at the confinement, he starts exploring the cave with the slaves who guide tours. As his health improves he becomes entangled in the mysteries of the cave and its inhabitants.
Elias realizes slaves are people, discovers another patient is not what he seems, and must decide who deserves loyalty.