One morning in San Francisco, an amazing thing happens. The Frisco Fly, a masked daredevil who climbs the city's building while avoiding the police, falls during one of his stunts. Onlookers rush over to the fallen Fly, who turns out to be Monk's bitter rival, and fellow patient of Dr. Kroger's, Harold Krenshaw. Miraculously, Harold survived the accident and is rushed to the hospital. Meanwhile, Monk is with Capt. Stottlemeyer on a secluded stretch of road investigating a burned out car wreck. There's a dead man behind the wheel and it looks like vehicular homicide... but Monk thinks the victim's death was accidental and that someone who happened upon the scene set the car on fire. But why would someone do such a thing? Monk is soon confronted with an even more baffling question when he hears the news about Harold Krenshaw. How can Harold, who has more fears and phobias than Monk, be the Frisco Fly?