Marius Dumont is eager to take the plunge into marriage in order to create a stronger base for the vampires and werewolves in Crimson City and to stop all-out human, werewolf, mech and vampire war. However, he has to get the support of the other leading vampires to marry a werewolf princess. They are eager for stability, but they feel his plan is foolhardy, particularly in light of his rumored infatuation with a human, Jill. The minor concerns of familial leaders seem petty in light of a potential werewolf/vampire plague.

Intricately interwoven with flashbacks to the days prior to the Blood Taint, when vampires and werewolves "began," CRIMSON AND STEAM demonstrates the levels of care with which Marius must balance politics and passion.