Three different people from three different parts of the world unite for one single mission i.e to save the human race. One is Glokta who has a lot of problems at hand because the enemies have invaded from all sides and the allies seem to be decreasing in number. People whom he has with him are not trustworthy anymore.
If things go on like this then he will surely have to surrender in front of his enemies or die while trying to protect the kingdom. Then there is Ladisla who has high aims and is trying to get back what was snatched from him. He has a large army that can help in fulfilling his quest but the army is not very well trained. The commanders of his army are worse than mere farmers in fighting.
The last one is Bayaz who is trying to investigate something connected to the past. These three need better allies and at this point they meet each other and realize that they are just perfect companions for one another. The issue remains which trouble these warriors i.e they don’t like each other. Their presence for one another becomes a constant headache.
Joe Abercrombie has never hesitated to add more than one primary character in the novels. When the author wrote The Blade Itself and Last Argument of Kings he did the same thing and here he plays with three main characters. We know that they can survive as long as they are together but staying together is an issue for them which Steven Pacey narrates till the end of the story.