Rain of Lightning
The corps is commanded to arrest a psi criminal, Bluettspur, from a backward world as of yet not part of the imperium. The mission is to be a surgical strike at the batallion level, to penetrate a psi community defense and take Bluettspur out.
Arriving at the scene, the strike force encounters space krakens defending the space around the planet, and the planet itself devastated by lightning storms. While going into the atmosphere, the force is dispersed and the platoon drop ships crash lands separatly. All attempts to communicate fails due to atmospheric disturbance, and a group of 6 marines set out towards the estimated landing site of another drop ship, to coordinate repairs.
En route the group encounters Bluettspur in company with local drow and duergar. An attempt at arresting him fails; he flees and the locals attack the marines. At the end of the conflict the marines questions a wounded former prisoner of Bluettspur.