The Forgotten Worlds Series by P.J. Hoover

When Benjamin stumbles upon a portal to another world in his hallway, he discovers he's not human, and must master his telegen powers in an otherworldly summer school.

At the end of summer school, Benjamin was given one task-find his missing brothers. Should be easy right? But Benjamin can't locate a trace of them anywhere until he interns at his father's office over spring break. There he finds a mysterious file written in ancient Lemurian with his name on it. Could the answers that Benjamin seeks be in the past?

The situation in Lemuria is rapidly deteriorating. In fact teleportation between the hidden continent and the outside world has become so dangerous, all agents and their families have been recalled.