Now back in the Empire following their sojourn overseas, Gotrek and Felix head north, to aid the men of the Empire in their fight against the invading Chaos hordes. Stopping off in Nuln, they meet up with dwarf engineer Malakai Makaisson, who is helping the Imperial war effort by transporting cannons to the frontline on his airship, The Spirit of Grungni. After a series of nasty accidents, it becomes clear that saboteurs are at work - can our heroes find the villains in time to save the day?