From the moment she first met him, Callie knew that Simon Montague was a dead man walking.

From rock-climbing to wing-suiting, the infuriatingly charismatic tech CEO lives every moment of his life like it might be his last—and given his packed schedule of adrenaline-fueled adventures, Callie calculated that statistically, one would be soon enough.

In order to secure funding for her groundbreaking work in astrophysics, Callie must work with Simon—and as much as she tries to resist it, the shy and play-it-safe scientist soon finds herself warming to his outgoing personality and thirst for life—the kind she had long since buried away.

But when the promise of a kiss is interrupted by Callie witnessing Simon literally flicker from existence, even her logical, rational mind struggles to find a scientific explanation. She learns that a supernatural phenomenon is threatening to tear Simon from reality itself—and only by facing her own dark and traumatic past can Callie learn what she needs to save the life of the man she's reluctantly developed feelings for.