Crime at sea is a classic plot, of course, but the second half of this article is an interesting setting: piracy in some regions has become so rampant that it is profitable for private entities to anchor ships stocked with weapons, armor, and mercenaries willing to provide security or respond to threats. The mercenaries are self-employed contractors; they pay the armory for lodging and transport to and from client ships.
The mercenaries often go weeks between jobs, which are high-risk and pay well; lodging is about $25 per night, but transport to a client ship can run into the thousands (you need it to get paid, don't you?). The lodging conditions are minimal and can be miserable: dirty, cramped, and full of aggressive men with little to do, competing for dangerous job opportunities. You're a long way from help, out of any country's jurisdiction, making ruthless pirate enemies with every life-or-death mission.
It strikes me that this is almost a dungeon-dive setting: figure your group of mercs leans toward the more corporatized, profit-sharing, less internal competition side. You get a call every now and then to rush off to a dangerous situation where you're expected to defend innocent life by violence, entering a friendly or enemy structure (ship) you don't know well, to search for and eliminate clear threats to life and/or property. The law is negligible, the authorities are impossibly distant, and the morality is stark. The survivors will get paid handsomely.