Ari Voss finds a projector in the basement of a condemned building. It opens doors into other worlds. There are forty-three symbols on its ring.

The first world Ari visits is alive - a city where the buildings themselves glow with bioluminescent light, where a woman named Meren is fighting to save her district's failing grid from a council that has already decided it doesn't matter. The city is strange and specific and real, and Ari fills a notebook with it.

Then the sky goes wrong.

Ari comes back through the door with a notebook full of a world that no longer exists, a projector with forty-two symbols left on its ring, and the beginning of an understanding that something is moving through the alternate worlds - something that is collapsing them from the edges inward, quietly, the way a light goes out rather than the way a bomb goes off. The people inside don't know what's happening until the physics start to fail. By then it's too late.

Forty-two worlds. A desert where lying is physically audible and a practitioner has spent twenty years protecting a community the market would destroy. A landscape where gravity follows attention and a child has a bruised shoulder because Ari didn't know that before stepping through. A city built on water where the wind and current move as one system, and a version of Ari three years ahead is making choices that Ari doesn't yet understand.

Something is killing the worlds in sequence. Ari has to understand why before the projector runs out of doors to open.

Written in the tradition of propulsive speculative fiction - specific, strange, and relentlessly forward-moving - Altverse is a novel about what happens when the map is the only thing standing between the worlds and the dark.