Genre: historical fiction (setting, Britain in the 7th century AD)
Wulfric is the youngest son of the king of Lindsey and guardian of the kingdom's border. His hopes are clear; to be a worthy leader of his warband; to protect the border lands from enemy raiders; to marry his betrothed, the beautiful Estrilda; and to support his idolised elder brother Aelfric, heir to the throne. When Lindsey is invaded by its predatory neighbour, Mercia, Wulfric and his small force fight a fierce rearguard action and make a bitter enemy of a Mercian warrior, Grimbeald. They arrive in the kingdom's capital to find that Aelfric has been mysteriously murdered, and the next day Lindsey is utterly defeated in a disastrous battle.
Wulfric has to flee for his life accompanied only by a few loyal friends. His ingenuity saves them from immediate capture but all Lindsey's former allies have changed to the winning side and there is a price on his head. Their situation becomes increasingly desperate until, hiding incognito in the wilderness, they are eventually given shelter on a remote hill farm.
Here Wulfric meets Morwenna, a woman his equal in intellect and courage. In defending the farm against raiders and in a dangerous clash with the local lord, they develop first friendship and then love. But Wulfric is still bound by his betrothal to Estrilda, obliged to avenge his brother Aelfric's murder, and owes a duty of protection to the people on his old lands. These loyalties tear him away from Morwenna, at great pain to them both.
Wulfric has discovered that Aelfric was murdered by Raedwulf, captain of Aelfric's own bodyguard. Following Raedwulf's trail, he finds out that Lindsey was betrayed on the eve of the battle and suspects Raedwulf of this crime too. He also learns that his old lands are being terrorised by Grimbeald, and that Raedwulf has been captured and taken there. This knowledge sends Wulfric back to Lindsey, despite the price on his head.
There he goes in search of Estrilda, thinking to rescue her, but is shocked and hurt to find she has happily abandoned him for a Mercian lord. She is being used, unwittingly, as the bait for a trap, and Wulfric only just escapes capture. Hiding from the pursuit, he encounters a refugee from Aelfric's household, and an object in her possession proves that it was Aelfric who betrayed Lindsey before the battle. Wulfric is horrified by this discovery; all his life he has looked up to Aelfric as his idol and tried to live up to him. Honour demands that he should still kill Raedwulf in revenge for Aelfric's death, but his own sense of justice insists that Raedwulf acted rightly and deserves to be found and rewarded, not punished.
Keeping one jump ahead of their enemies, Wulfric and his friends follow Raedwulf and Grimbeald to their old lands on the border, where they join forces with the local population and destroy Grimbeald in an ingenious ambush. Raedwulf believes Wulfric is still seeking vengeance and flees into danger. Wulfric tries to save him, but when Raedwulf realises that Wulfric knows of Aelfric's dishonourable betrayal he tries to kill Wulfric to protect Aelfric's reputation, even though this results in his own death.
For the first time in his life, Wulfric is no longer in his brother's shadow. When the local population acclaim him as King of Lindsey, he accepts it in his own right. But he is pragmatic enough to know that he does not yet have the strength to overthrow Mercia. For that he needs a large military following and political allies, which will have to be sought in other kingdoms. So he goes into exile with a handful of loyal followers, having lost his idol, his woman and his lands, but having gained a new and greater ambition.
The main theme of the book is loyalty and its limits; e.g. loyalty between a betrothed couple, loyalty of followers to a lord, loyalty of a lord to his people, loyalty within a family, and loyalty to a kingdom. All of these figure in the plot and some of the characters hold to their loyalties and some do not.
If you write the synopsis well enough, the theme is clear. I think you did.
This is good because it sets up the world we “join in progress” and gives us a starting point for what happens next. The characters’ motivations are clear; you’re not awash in events. I don’t read enough historical fiction to know if this is a rehash of every other 7th Century AD book under the sun, but I don’t see any surprises or “aha” turns in the plot. I also see the women are all subordinate characters and only love interests. That would be a big "ugh" for me.