The salvage you brought to the Cardinal only raised more questions, as it was so waterlogged and rotten that it can't have come from a seaworthy vessel. Luckily a survivor has been fished out of the water by some pirates. Now someone needs to convince the pirates to give up that man. That would be you and a few inquisition ships the Cardinal has requisitioned.
This is a sea battle against three opponents. The flagship will be level 46 and the two guards both around level 40-41. You'll have two NPC ships to help you and need to defeat the flagship in boarding combat.