The Grim Skulls are a small mercenary organization that operates in the Skyllian Verge. The group is made up of a few dozen armed thugs and criminals who possess basic military training. Their activities caught the notice of Saren Arterius after they attempted to purchase a shipment of military-grade weapons stolen from a turian transport freighter. While normally a matter he would turn over to the local authorities, Saren decided to deal with everyone involved in the illegal weapons deal personally after discovering that there were turians among the sellers, and humans among the group of Grim Skulls buyers.
The smugglers' and Grim Skulls' operations are decidedly amateur, and Saren is able to wipe most of the participants out single-handedly while they argue about the terms deal in a warehouse on Juxhi. Before being executed by Saren, an injured human member reveals that the Blue Suns mercenary group were the original buyers and had a major operation planned, but pulled out of the deal in order to avoid the attention of the Spectres.