It is 40 years into the future and the world is in turmoil. A plague has destroyed humans' ability to conceive females, or so Callum thinks until he meets Bo. A page-turning adventure unfolds as the pair rely on each other to survive a dangerous journey to a safe haven in the city of Vulture's Gate.

One girl - could she be the last girl alive? One boy, pursued by reckless men who have kidnapped him from his fathers.

Bo and Callum go in search of a safe haven, a place to call home. But where can they turn and who can they trust? When every stranger is a threat, does their only hope lie in reaching Vulture's Gate?

Following a journey that takes them across barren deserts and lost valleys, Bo and Callum must discover how to survive alongside runaway boys and crazed religious terrorists, in a world with an uncertain future.

And what is the disturbing secret at the ruined city's core?