After nightfall, David Caine inhabits a world of risk, obsession, rich rewards, and sudden, destructive downfalls. A compulsive gambler possessing a brilliant mathematical mind—and an uncanny ability to calculate odds in the blink of an eye—he prowls the underground poker clubs of Manhattan, winning more than he loses. But Caine is a man prone to crippling epileptic incidents—and one night he makes a costly miscalculation, suffering the most intense seizure he has ever experienced. And his life spins madly out of control.

Desperate to regain his equilibrium, he agrees to test an experimental drug with unnerving side effects. Suddenly he is having visions of the past, present, and future; either peering through a window into an alternate reality or teetering on the precipice of a psychotic breakdown. Chemistry and destiny have colluded to grant David Caine the astonishing ability to foresee the consequences of his actions and the probability of various outcomes, both good and terrible.

But with his "gift" comes grave danger, for he is not the only one who knows his secret. Frightening powers operating from the shadows now want him for their own, forcing Caine to seek help from a most improbable ally—a beautiful rogue CIA agent skilled in the death arts—on a desperate race for survival with his sanity hanging by the slenderest of threads.