Humans escape an overpopulated future-Earth in the virtual reality world known as Frontier. Seth is an avid player until he receives a cryptic email using his real name—a violation of Frontier’s rules. He follows a virtual trail to an unnerving discovery, the sender’s address falls outside the bounds of his world’s network. The revelation forces him to consider the one question he’s refused to ask: could the sender be from inside the game?
His exploration of the origin of Frontier's frighteningly real characters leads to an alliance with Leith, an inhabitant of Frontier and the bane of Seth’s existence. As they investigate, Seth and Leith's tumultuous relationship goes from hellish to heated, and Seth comes to the horrifying realization that he might be falling for him.
When Leith is nearly killed by Frontier personnel and Seth’s friend ends up in a coma, Seth discovers the truth: the world behind Frontier is called Thea, and it’s real. The game is a doorway for the Frontier developers to colonize Thea, but first they have to get rid of the locals.
To save Thea, Leith and Seth must work together to sever the link between their worlds, but it means they’ll have to give up the one thing that’s taught them how to live—each other.