The Wild Riders of Saim Hann craftworld are renowned for their skill and daring, none more so than their headstrong Wild Lord, Nuadhu Fireheart. Having been approached by a representative of Yvraine, emissary of the Whispering God, Ynnead, Nuadhu has unwittingly awoken a slumbering threat – a tomb world of the aeons-old necrontyr. Now, Clan Fireheart must seek alliance with the Ynnari in order to combat the threat to their craftworld, and preserve their honour and the future of the family. The two forces return to Agarimethea to destroy the necrontyr before their strength becomes unassailable. But for what other purpose does Yvraine accompany Nuadhu and his kin, and what exactly is her interest in Naiall Fireheart, the ailing chieftain of the clan?