The Code Merlin
Tavish Bell is a Crey representative, who is authorized to contract out jobs deemed too difficult for Crey to handle on its own. One of those jobs happened to be a 'Code Merlin', a magical mishap in one of their labs. When you arrived in the lab you found it to be riddled with smoke and fires, and an air of dread surrounded you. You encountered many possessed scientists and eventually a demonically possessed Paragon Protector. You quickly deduce that this Protector is the cause of all this mess. Crey must have been experimenting with hybriding their Protectors with some demons from the Netherworld, and now you get to pick up the pieces, for a nice paycheck of course.
Tavish informed you of a shipment of weapons being imported from Paragon City to fight off the demons that escaped. Unfortunately the demons found out about this shipment and attacked the cargo ship before it could get to the Rogue Isles. You boarded the ship and secured the weapons, defeating many of the escaped demons in the process. You turned over the weapons to Tavish, so that Crey could finally clean up this mess themselves.
You then met with Tavish and he informed you that even with the weapons you secured, the Crey security was no match for the demons. He had the location of the Archdemon who masterminded everything. He was holed up in a sewer. You fought the Archdemon in the sewer, defeating him and severing the ties that bound his minions to this plane. Crey then made their promised deposit.
NOTE: As of Sept 05 2006, the souvenir text states that you fight the Archdemon in a sewer, but the actual mission is in a modified Crey Technology Lab mission map.