The Ice merman

An accidental rescue

3 pm in the Kraken pub, the sky is blue and my glass full of beer. "He killed the merman and take the scale you can see here from him!" Scream Martin. Martin is the one who owns the pub, if you have the misfortune to go here for the first time, you can be sure that he will tell you his extraordinarily epic story of when his grandfather killed a merman. The war between human and merman stopped 80 years ago but his family still brag about it!
Suddenly one of my informants walk in and says: "Captain we need you!" Me and my crew we jump on our feet and follow him to our ship. On the way, he explained why did we had to give up our beers: " The Ship of Captain Moriarty left the harbor 30 minutes ago, they will try to attack another ship who must supply the city!" Bloody Moriarty, it's been 3 weeks since he sunk all the ships that are supposed to bring food to the city. We have to stop him now! I know that usually pirates wouldn't care about that, but me and my crew we decided to protect this city from the sea.
Finally we arrive and starting to leave the harbor. Fortunately, we know where they are going, I hope we won't be there too late.
"Captain, straight ahead, they're here!" Shit!They already sunk the ship! But we still can take back the food and bring it to the city.
We reach and start to fight, they are more than us but we are stronger. We manage to get the upper hand and we defeat them. After months of work we finally catch him! Moriarty the most clever pirate I've ever seen, and his right-hand man, Sébastien Moran! I was going to go talk to them when Steven says:
"Captain can you come? "He is in the hold, I go there and then I see... A merman! He look young, has black and curly hair and he is tied. I free him from the rope and tell him: "Hi, I'm Gregory Lestrade but everyone call me Greg. Are you okay? "