When an invaluable item is stolen from the Royal Palace by pirates residing in the lawless archipelagoes, in 17th century Stockholm, a newbie officer must choose between his duties to the crown and his childhood love who was exiled to the islands many years ago.

Hi PetronellaLäckgren,

Let us break down your logline into segments and see it from the readers’ POV.

1- It’s the 17th century, Stockholm.
2- An invaluable item is stolen from the Royal Palace by pirates residing in the lawless archipelagoes.
3- A newbie officer must choose between his duties to the crown and his childhood love
4- The newbie officer’s childhood love was exiled to the islands many years ago

Now let us see if we can find the relation between segments of the story (if there are any).

Do you see where I’m going with this?

I think you should connect the segments by mentioning their relation. I think you should remove unnecessary info and re-write it.

I hope this helps
Good Luck