The Fold is destroyed, Alina seems to have lost her powers and retreated to Keramzin with Mal, wearing a disguise.
The Darkling has been burned on the pyre and seems to be gone for good.
Nikolai is left with a demon and a broken country to rule over, on his side the important Triumvirate.
Ketterdam has its own war between the gangs of the Barrel and the richer people, with Kaz Brekker and his crows being the biggest danger in the city - at least from the viewpoint of the merchants.
And then there is this new drug, jurda parem, that's becoming a danger to Grisha all over the world. The highly addictive drug enhances Grisha abilities and makes the impossible possible, but it comes with a high price. Over time it kills Grisha slowly. It's extremely rare to survive it and if someone does, it twists the Grisha gift.
Shu Han is creating new soldiers, the Khergud, turning humans into half machines, making them weapons.
And Ravka sees new problems too; Sainthood for the Darkling is requested by a group of people and West Ravka is still majorly fighting for independence.
Grisha and Otkazat'sya disappear seemingly without a trace and rumours about an unnoticed island at the True Sea become louder.
The story is settled between the end of the Shadow & Bone Trilogy and the King of Scars duology and offers an alternative timeline to what happens in the books. And where the story goes is up to you.