When 12-year-old Lachlan Smith found a portal to a hundred years in the future, he discovered a world where the human species had been extinct for decades. Now Lock and a small group of his friends and family are exploring the ruins of the future to learn its secrets. At the same time, they're trying to keep those secrets from the world of the present and prevent the time portal from falling into the wrong hands… all while maintaining the semblance of a normal life.

The more they find, the more they realize that if they're going to prevent the end of the human race, they can't do it by themselves. But who can help them? And who can they trust with the portal and the power it represents — the power to reshape the future… or destroy it?

For Locksmith, new discoveries, hard choices and dangerous journeys await.