Serpentus

Dispatched to Stone Hill to oversee the city's defenses among nebulous rumors of the Shadow Council's threat, Owen Greenwaters must rely on the city's guard and its natural defenses to protect the citizens.
But when an army of mythical hooded ones bolstered by a sea serpent and the Soulless arrive in the wake of a terrible storm, he knows there is little he can do beyond hope the walls hold - and pray to the gods he and Stone Hill's people will survive.
They are outnumbered, outmatched, and without magical support. Owen is the only knight present in the city. They will be overrun.
The Soulless are merciless and rarely take prisoners, but Owen and the survivors of Stone Hill are exceptions...
And some fates are worse than death.