George is determined to keep his promise to Amy: no more heroics, no daring ventures, no unnecessary risk-taking. When their refuge is destroyed, however, they are plunged back into the battle and must make their way to Canada in search of vital materials.

Martian sympathisers, a dangerous sea-voyage, an audacious heist and run-ins with untrustworthy allies are only a few of the challenges George and Amy must endure. Can they succeed, and return with new weapons to use against the Martians? Or will they witness humanity's last days?