2021’s A Drowned Kingdom is the first volume of P. L. Stuart’s secondary-universe sword-and-sorcery Drowned Kingdom Saga
The kingdom of Atalantyx is the greatest nation in the world. If you doubt this, simply ask Atalantyx’s Second Prince Othrun. He belongs to the kingdom’s royal family so must be an unimpeachable source. An inflexible, devout follower of the One God, Othrun holds his convictions without any trace of doubt or reflection. Having been placed by birth near the top of the kingdom’s pecking order, Othrun is confident that the world is as it should be; reform or deviation is therefore unthinkable.
However, Othrun is not the heir to the throne. His older half-brother Erthal is. Erthal is quite different from his brother.