In Jack and the Geniuses: Lost in the Jungle, famed inventor and scientist Henry 'Hank' Witherspoon has gone missing, and it's up to Jack and his brilliant siblings, Ava and Matt, to track him down.

When the kids arrive at Hank's lab one morning to find the facility ransacked, and their friend missing, they also discover clues to the project he's been working on in complete secrecy - a revolutionary new way to generate and store electricity inspired by the electric eels of the Amazon River.

(Jack's idea, but no one seems to remember that.) Unfortunately, the trio aren't the only ones who've figured out what Hank has been doing. Several others are trying to locate Hank and steal his big idea, including a rival inventor, a disgraced scientist, a once-popular Brazilian boy band, and the great J.F. Clutterbuck, the genius behind the odorless sock.

The kids travel to Brazil, then venture deep into the Amazonian jungle in search of their mentor, following a series of subtle clues that Hank has left along the way. Relying on a mix of intelligence, cunning, and wild new technology, the kids have to overcome strange creatures, a raging river, a dangerous jungle, and some very clever foes to find their friend and protect his big idea.

Like volumes one and two, Lost in the Jungle features a glossary of terms and an experiment kids can do at home or at school.