This is the third book in a series which you will either love or hate. It is also one of those multi-book series which must if at all possible be read in the right order, which is
1) The Game of Kings
2) Queen's Play
3) The Disorderly Knights
4) Pawn in Frankincense
5) The Ringed Castle
6) Checkmate
The disordely knoights of the title are the knights of St John of Malta. This book also features a battle of wits and intrigue betweem the central character, Francis Crawford of Lymond, and his great enemy Gabriel.
There are two reasons why this series, and indeed the author's similar "Niccolo" series, should be read in chronological order. The first is that the plots are incredibly complicated and if you read them out of sequence you have no chance of understanding what is going on. The second is that many of the characters meet their deaths in ways which are exceptionally unpleasant both for themselves and for the characters who survive them. If you read one of the later books first, advance knowledge of how characters are going to die, and the effect it will have on surviving characters can have an impact on the pleasure you would otherwise have had in reading about them for the first time.
Like the books, the central character, Francis Crawford of Lymond, is brilliant, violent, and extremely complicated. Unlike the books he is very flawed. Lymond is a mercenary with particular interests in Scotland and France, and gets involved in nefarious deeds all over the world as 16th century Europeans knew it. Dunnett brings the splendour, cultural ferment, and violent cruelty of the Renaissance world splendidly to life.
If you are at all squeamish, or do not like having to make your brain work overtime to follow a book, leave this series alone. Lymond's story is neither "chewing gum for the brain" nor a comfortable read. And even if you prefer flawed heroes to knights in shining armour, Lymond may infuriate you from time to time. But if you can put up with these features, these books will richly reward the effort you make in reading them.
There is no middle ground: you will either hate the Lymond series or recognise these books as one of the greatest works of historical fiction ever written. Or very possibly both !