Harry Poole, a young man who suffers from bipolar disorder, enrolls in Dr. Lanyon's clinical study to test a new drug. Experiencing positive results, Harry embraces his renaissance and creates an alter-ego for himself. "Edward Grey" thus is born. Confident, charming, and fearless, he is the man Harry has always dreamed of being. Witnessing strange behavior among other test subjects, Dr. Lanyon abruptly discontinues the trial. Before Harry leaves the hospital, Anna, a nurse "Edward" has seduced, gives him a surplus of the pills. Intoxicated by the rush he gets from being Edward, Harry begins to lose himself in his new persona. But Edward becomes more and more volatile and aggressive. Harry can barely control him anymore and Edward, in a fit of rage, kills a man. Lost and confused, Harry doesn't know who he is anymore. One moment he is devastated by all the terrible things Edward does, but the next he takes a pill and surrenders himself to his evil side. As Edward spirals further down into madness, the battle for Harry's soul begins.