Graduating from UC Berkeley just as the Summer of Love begins, twin brothers Jack and Bobby Doyle forge two different career paths. Jack heads off to Vietnam to serve his country, while Bobby remains in the Bay Area, immersing himself in the world of music journalism. As the summer progresses, both brothers witness death firsthand for the first time, Jack on the battlefield and Bobby on the drug-infested streets of San Francisco's Haight-Ashbury district.

Their experiences are equally shattering, with Jack losing newfound comrades-in-arms and Bobby enduring the murders of two women he'd grown close to. Bobby's traumas become as threatening as Jack's daily perils when he falls under suspicion in the murder investigations. Conferring with Jack by letter, Bobby tries to discover who actually committed the crimes. As the Summer of Love draws to a close, stunning events overtake the entire Doyle family.