Wide receiver Marvin "Shake" Tiller and running back Billy Clyde Puckett are two close friends on a Miami professional football team owned by the domineering "Big Ed" Bookman. Living under the same roof as the team buddies is Bookman's daughter, Barbara Jane, which sets the stage for an intricate love triangle among the trio. At first, their relationship remains platonic, but as Shake gains newfound confidence from a self-improvement course led by the enigmatic seminar leader, Friedrich Bismark, things start to shift. This program, known as Bismark Energy Action Training, or B.E.A.T., transforms Shake, leading him to develop romantic feelings for Barbara Jane.
As the connection between Shake and Barbara Jane intensifies into a sexual relationship, they set their sights on a future wedding once the football season wraps up. However, challenges arise since Barbara Jane is not a participant in B.E.A.T. Shake is cautioned by Bismark with a stern warning that “mixed marriages don’t work.” Undeterred, Barbara Jane decides to join B.E.A.T., hoping to understand Shake better. This decision quickly becomes a grueling ordeal; after enduring what she describes as Bismark's "sadistic abuse, pious drivel, and sheer double talk," she finds herself exhausted and guilt-ridden over her inability to grasp the program's principles.
Meanwhile, Billy Clyde harbors his own feelings for Barbara Jane, leading him to act without informing either her or Shake about his intentions. He secretly joins the same B.E.A.T. training session, aiming to empathize with her struggles. Billy Clyde manages to navigate the absurd rules of the seminar, which forbids bathroom breaks and social interaction among attendees, displaying remarkable resilience. As feelings are brought to the surface during one particularly intense session, he offers a cathartic expression of his deepest emotions, shocking his fellow trainees. Shake, surprised to see Billy Clyde emerge from the training, learns that his friend had initially joined the program to mock it later but claims he genuinely "got it."
Despite Billy Clyde's reassurances that Barbara Jane's lack of understanding doesn’t matter, Shake's apprehension grows. During their wedding ceremony, as Big Ed proudly walks Barbara Jane down the aisle, a surprising turn of events occurs. When questioned by the minister, Shake pauses and ultimately declares "no," rejecting marriage. This startling declaration incites rage in Big Ed, who responds with threats of trading Shake to an undesirable team, resulting in chaos as he punches Bismark, instigating a brawl.
In the midst of the turmoil, Billy Clyde inadvertently reveals his earlier pretenses to Barbara Jane, prompting her to question everything she thought she knew about her situation. As they navigate the ensuing commotion together, a spark ignites between them, leading them to explore their true feelings for one another while strolling along the beach, still dressed in their wedding attire.
