How much does your world affect who you are?

In Kat Garcia's world only the Rocky Mountains are above sea level and the sun is hot enough to kill. She goes through a mysterious window seeking weapons to keep her friends safe from the remnants of the decayed government.

In Kaitlin Garcia's world the Unified States is constantly bombarded by severe storms. She goes through a mysterious portal to implement her climate mitigation strategy before her world becomes uninhabitable.

In Katherine Garcia's world only draconian government control over the citizens has kept the droughts, floods, and diseases from killing everyone. She goes through a mysterious portal seeking nuclear fusion to throw off the oppressive governmental yoke.

When the actions of the three Kats start to destroy the universes, can they join forces and save them?