"Professor Summerfield, your very presence here has raised this hotel's insurance premiums by seven point two percent."

It is the year 2595. Mars, once the distant target of humanity's ambitions in space, has been colonised for five hundred years. To mark the anniversary, the planet's university is holding an academic conference. Naturally, esteemed expert on Martian archaeology Bernice Summerfield is invited to present a paper based on her long career in this field.

But other matters distract Bernice from academia. Decades ago, hostile aliens invaded Mars. At their moment of greatest need, Mars' human population was betrayed by its leader. And although the occupation was swiftly ended, the anger of those who fought to save Mars still runs deep.

So when a veteran of the war is found dead, old wounds are reopened. Bernice finds herself investigating a murder with the least reliable of allies — and soon discovers that the consequences of the Siege of Mars are far from being ancient history.