Months after the expedition through THE PORTAL, Tyler Drake is still struggling with the gruesome consequences. So the call for help from Mexico comes just in time: Adriana's brother is missing – and seems to have made the journey alone to the world beyond the cave.

Another race against time begins – and this time the team has to contend with not only the dangers of an exotic world, but also with terrestrial adversaries and an extraterrestrial threat, the existence of which they never even suspected. Will they succeed in saving not just one boy, but an entire world?

Portal Science Fiction – an underwater star gate.