The Last Meridian. The Living Geometry Trilogy, #1

A disgraced cartographer. Five kingdoms on the edge of collapse. A world where borders are not lines - they are debts coming due. Caius Maren was once a surveyor of rare precision. Then he falsified a border, ruined lives, and lost everything that gave his name authority. Now, in a rented room above a cooperage, a crack appears in the wall - not through the plaster, but through a boundary line Caius drew years ago in shame.
When he measures it, the bearing is impossible. The crack matches the hidden geometry of a border the official maps say should not exist. Soon, the same impossible drift appears across harbour markers, certified surveys, ancient records, coastal charts, and disputed lands. Fields vanish into old forest overnight. Boundary stones disappear without trace. Villages remain in legal registers while the ground beneath them forgets they were ever there.
The five kingdoms call it collapse. But the older records suggest something far more dangerous. The land may not be dying. It may be correcting itself. To uncover the truth, Caius must join forces with Sable Orin, an exiled navigatrix of the Tidal Conclave, and confront the institutions that turned living geography into fixed law. But every measurement exposes another lie, every court delays, and every kingdom has more to lose from the truth than from the unmaking itself.
Because if the borders fail, the map of the world will fall with them. And if the borders hold, the old wounds may never heal. The Last Meridian is Book One in an epic fantasy trilogy of broken maps, political power, ancient geometry, and the cost of drawing false lines across a living world.