The Joshua Files: Invisible City by M.G. Harris

Josh's father has been reported dead in a plane crash. He had been searching for a lost Mayan Codex, a book that many  disappeared trying to find. And when the news comes in that Josh's dad died of strangulation before the plane crashed, Josh knows he has to go to Mexico to find the truth.

This first novel in the action-packed Joshua Files brings Josh to the depths of the Mexican jungle and into a secret society existing beneath an ancient Mayan Pyramid. Sucked into a vortex of intrigue, Josh becomes a target for danger as he learns that his family holds the key to solving the mystery of the 2012 prophecy. Can Josh find the missing codex in time to save mankind?

~from publisher's description