Four Kats. Four worlds. One multiverse worth saving. Across parallel Earths pushed to the edge by climate disasters, political collapse, and runaway technology, four versions of Kat Garcia fight to change the futures they've inherited. In one world, grad student Kathy Garcia uncovers a breakthrough in fusion research—then risks her life to send a neutrino warning back through time, hoping to alter the course of climate catastrophe. In three others, Kats step through mysterious portals seeking what their worlds desperately lack: weapons to defend vulnerable communities, climate‑mitigation strategies powerful enough to halt escalating storms, and the promise of nuclear fusion to overthrow an oppressive regime. But each bold choice sends ripples across the multiverse, threatening to unravel the very realities they're trying to save. To stop the collapse, the four Kats must confront their own assumptions, join forces across universes, and face the consequences of their intertwined destinies. Their journeys continue in ten sharp, surprising short stories that explore the aftermath—new alliances, new threats, and the final reckoning that brings the entire saga to a close. This omnibus collects the complete Kat Cubed universe: a multiverse‑spanning tale of science, survival, and four extraordinary women determined to rewrite their worlds.