Lois McMaster Bujold is a great multiple award winning author who will be forever remembered for her Vorkosigan series. One of her most captivating features is her ability to write believable characters no matter if they are in a sci-fi or fantasy setting.
In the past four years she's penned the four books of the Sharing Knife series. Horizon is the fourth and final book in the series and really isn't intended as a jumping on point.
The series focuses on Dag, the Lakewalker, and Fawn, the farmer. Lakewalkers are a soldier/magician class that protect the Farmers from Malices (evil magical creatures). As is to be expected neither group really understands the other very well and this causes no end of problems and it makes the pairing of Dad and Fawn so odd.
The first two books are about Dag and Fawn coming together while the third and fourth are about their attempts to bring Lakewalkers and Farmers closer together. Interestingly enough this is the second book in a short period I've read where co-operation seems to be the way to solve problems over an every man for himself approach.
In this final book Bujold uses her deft hand with characterization to bring things to a satisfying conclusion. She ties up the dangling plot threads and you can chart the personal growth of many of the characters from book one to four. Once the story concludes you get the feeling that the characters lives will continue on even if we won't be privy to it.