Elina Reyes (The Long Version Trilogy Book 1)

The brain tissue that lets Dr. Elina Reyes step between worlds is still growing, and it will kill her. Her only way out is to build a new home for her mind. But a self can't be copied: there will never be two of her, not for a second. No backup. No rehearsal. One crossing, into a machine buried under a mountain in the far north.