In the vibrant, sun-drenched summer of 1964, ambitious aspiring drummer Guy Patterson is recruited by the charismatic lead singer Jimmy Malone and sweet-natured rhythm guitarist Lenny Haxton to join their band for a local talent show. Needing a replacement percussionist after an injury, they turn to Guy, whose relentless, frantic pacing transforms their slow ballad into a wildly infectious, upbeat pop sensation. Driven by Jimmy’s fiery ambition and the band’s undeniable chemistry, the group rebrands as The On Wonders, soon shortening it to The Wonders after a humorous
misunderstanding by a radio announcer.Desperate for success, the band enlists Jimmy’s gorgeous and fiercely loyal girlfriend, Faye Dolan, as their de facto manager. Faye anchors the group as they win the talent show and quickly catch the attention of shrewd talent manager Mr. White. Recognizing the undeniable commercial potential of their catchy debut single, "That Thing You Do!", Mr. White signs them to a major record label and whisks them away on a whirlwind national tour.As fame crashes over them, the dynamic within the group begins to fracture. The unnamed bass player, constantly overshadowed and bewildered by the sudden stardom, quietly abandons the group in a hotel lobby, replaced on the fly by a brooding, jazz-loving bassist known only as "T.H." Meanwhile, Jimmy becomes increasingly arrogant, consumed by rock-star delusions and alienated from Faye, who feels pushed aside by his obsession with fame and female adoration.The tipping point arrives during a high-profile television appearance in Los Angeles. Tensions boil over when Jimmy abandons the band on
live television to chase a fleeting solo opportunity, sparking a furious backstage confrontation. Lenny, disillusioned by the chaos and homesick for his normal life, also walks away. Amidst the sudden disintegration of the group, Guy finds solace and romance with Faye, realizing that the pure joy of making music mattered far more than the synthetic trappings of pop stardom.Following their brief, meteoric ascent, the band officially disbands, each member taking a different path. Jimmy pursues a solo career in California, while Lenny opens an appliance store. Guy, however, finds true fulfillment by marrying Faye and joining a legendary jazz ensemble, finally playing the complex rhythms he always loved. Ultimately, the movie captures the bittersweet, ephemeral nature of youth, ambition, and the magic of a single, unforgettable summer when a group of ordinary kids caught lightning in a bottle.