Stone-Hearth Hold is famous for one thing: the Great Dome, a vaulted ceiling so perfectly carved that it has stood for eight hundred years without a single reinforcement. Master Mason Fenna Deep-Shore has spent her career maintaining it, using the ancient stone-singing techniques passed down through generations of her guild.

But the Dome is cracking.

Chief Crystal-Engineer Jorik Spark-Hammer has a solution: reinforce the stone with resonance-crystal lattices, creating a hybrid structure that combines stone-singing with crystal engineering. It's revolutionary. It's untested. And to the conservative elders of Stone-Hearth, it's heresy.

To prevent the Guilds from tearing each other apart while the Dome crumbles overhead, the Council orders a Guild-Marriage — a political union that binds Fenna and Jorik together in both work and life. Neither wants it. Fenna sees Jorik as a reckless outsider. Jorik sees Fenna as a stubborn traditionalist.

But as they work together, they discover the damage to the Dome isn't natural. Someone is sabotaging the stone — a faction within the hold that wants to prove the deep holds are no longer safe, that the future lies on the surface.