Plot
Claude Hooper Bukowski sets off from Oklahoma to New York City, where he is being drafted into the Army. Before his draft board appointment, Claude explores New York, where he encounters a close-knit "tribe" of hippies led by George Berger. He observes the hippies panhandle from a trio of horseback riders, including Short Hills, New Jersey debutante Sheila Franklin. He later catches and mounts a runaway horse (which the hippies have rented), exhibiting his riding skills to Sheila ("Donna"). Claude returns the horse to Berger, who offers to show him around.
That evening, Claude gets stoned on marijuana with Berger and the tribe. He is then introduced to various race and class issues of the 1960s ("Hashish", "Colored Spade", "Manchester", "I'm Black/Ain't Got No"). The next morning, Berger finds a newspaper clipping that gives Sheila's home address. The tribe members — LaFayette "Hud" Johnson, Jeannie Ryan (who is pregnant), and "Woof Dachshund" —crash a debutante party purportedly so that Claude can meet Sheila before he gets drafted. Sheila secretly enjoys her rigid environment being disrupted ("I Got Life"). After the hippies are arrested for trespassing, Claude uses his last $50 to bail Berger out of jail, where Woof resists having his hair cut ("Hair"). When Sheila is unable to borrow any money from her father so that Berger can get the other members of the group out of jail, Berger returns to his parents' home, where his mom gives him enough cash to bail out his friends.
They subsequently attend a peace rally in Central Park, where Claude drops acid for the first time ("Initials", "Electric Blues/Old Fashioned Melody", "Be-In"). Just as Jeannie proposes marriage to Claude, explaining to him that marrying her will exempt him from the draft, Sheila arrives to apologize. Claude's "trip" reflects his inner conflict over which of three worlds he fits in with: his native Oklahoman farm culture, Sheila's upper-class society, or the hippies' free-wheeling environment.
Following his "trip", Claude falls out with Berger and the tribe members, ostensibly due to a practical joke on Sheila (taking her clothes while she's skinnydipping, compelling her to hail a taxi in just her panties), but also due to their philosophical differences over the war in Vietnam and over personal versus communal responsibility. After wandering the city ("Where Do I Go?"), Claude finally reports to the draft board (“Black Boys/White Boys”), completes his enlistment, and is shipped off to Nevada for basic training.
It's now winter when Claude writes to Sheila ("Walking in Space"), who subsequently shares the news with the others. Berger devises a scheme to visit Claude. Meanwhile, Hud's fiancée — with whom he has a son, LaFayette Jr. — wants to marry as they had planned earlier ("Easy to Be Hard"). The tribe members trick Sheila's brother Steve out of his car, then head west to visit Claude.
The hippies arrive in Nevada where Claude is stationed ("Three-Five-Zero-Zero", "Good Morning Starshine"), only to be turned away, ostensibly because the base is on alert, but also because the surly MP on duty does not care for their looks. Sheila proceeds to chat up army sergeant Fenton at a local bar, luring him to an isolated desert road where the hippies acquire his uniform and car. Berger cuts his hair and dons the uniform, then drives onto the Army base. He finds Claude and offers to switch places with him for the next headcount, so that Claude can meet Sheila and the others for a farewell picnic in the desert.
Just after a disguised Claude slips away to the picnic, the base becomes fully activated with immediate ship-outs for Vietnam. Berger's ruse is not discovered, and he is herded onto a plane with the rest of Claude's company. Claude returns to the empty barracks and frantically pursues Berger's plane, but is unable to reach it before it takes off for Southeast Asia ("The Flesh Failures").
Months pass. Claude and Sheila—along with the rest of the tribe—gather at Berger's grave in Arlington National Cemetery; the grave marker verifies that Berger was KIA in Vietnam ("Let the Sunshine In"). The film ends showing a mass peace protest in Washington, D.C.