Heartlight is the story of Bradley's greatest champion of good, Colin MacLaren. Ghostbuster, exorcist, psychic investigator par excellence, student and teacher of the mystic arts, Colin began his fight against Darkness during the grim days of World War II. Heartlight opens just after the end of the war, with Colin's return to America.

In the early days of what will become the Summer of Love, Colin meets Claire Moffat, the great psychic sensitive who will be his dearest friend and closest companion for decades to come, when he rescues her from a cult bent on human sacrifice. The leader of that cult, Toller Hasloch, becomes one of Colin's greatest enemies. Working behind the scenes for the next thirty years, Hasloch manipulates politics and the economy to turn America away from the Light. Decades pass before Colin becomes aware of Hasloch's manipulations. He's too busy saving people and teaching the next generation of psychic warriors.

When Colin at last realizes the strength of Hasloch's evil, it is nearly too late. Colin is no longer young; he has no disciple by his side; and he has begun to feel that Light can never truly triumph over Darkness. Still, Colin MacLaren is the only one who can face Hasloch and the hellhounds the younger man has unleashed. He must fight on, while the fate of America, and perhaps all mankind, hangs in the balance.