Dean Koontz's Nevermore #1
From the moment they first met, Bobby Godric and Nora Watson were meant only for each other. Together, the two built an empire from their true love and hard work. Young, brilliant, and wealthy, the entire world was open to them until fate cruelly intervened, and Nora died suddenly. Bobby Godric won't take the loss of his soulmate lying down.
Backed by a team of brilliant minds, Bobby invents Project: Nevermore, a way to travel to parallel worlds, searching among infinite earths for an exact, duplicate version of the love of his life. But when his travels attract the attention of THE HYDRA, an alien race conquering every Earth they can find, Bobby finds himself drawn into an ancient war he never dreamt existed, fighting to save humanity from a threat on the verge of extinguishing mankind forever. All for the sake of love.