On an ordinary day at Gordon High, Ben Ross shows his history class a film about the Holocaust as part of their unit on World War II. While some students—like the popular and bright Laurie Saunders, editor of the Gordon Grapevine, and her best friend Amy Smith—are moved by the film, other students like Laurie’s boyfriend David Collins, a self-centered running back for the football team, barely bat an eye. The class “creep,” Robert Billings, even falls asleep midway. Ben Ross is intrigued by his students’ varied reactions to the film but perturbed when he finds himself unable to answer Laurie and Amy’s questions about how ordinary Germans could have turned a blind eye to the atrocities committed by the Nazi Party—or worse, could have joined their ranks.
At lunch the next period, Laurie and Amy remain disturbed by the images from the film, but David Collins and his best friend Brian Ammon wolf down their lunches, immune to what they’ve just seen. David tells Laurie that he sees the Holocaust as “a piece of history”—something that can’t be changed, and certainly won’t be repeated. Laurie and Amy’s moods lighten over the course of the rest of the school day, and they laugh and joke in the Grapevine offices with the class clowns Alex Cooper and Carl Block.
That night, Ross is determined to look through every history book on the second world war he can find to try and discern the answer as to how groupthink and coercion enabled the Nazis to gain so much indisputable power—but discouraged when he still can’t find the answers. Ross begins to wonder if, perhaps, an experiment that replicates the conditions of Nazi Germany is the only way to find the answer—so he begins devising an exercise for class the next morning. Ross’s wife Christy admires her hardworking husband and encourages him to search for the answers he needs, but secretly worries about his obsessive tendencies.
The next day, Ross begins an experiment with his senior history class. He writes the words “STRENGTH THROUGH DISCIPLINE” on the board, institutes several new strict, militaristic classroom rules, and runs his students through physical and intellectual exercises like a drill sergeant. He is shocked when his normally sluggish, sloppy students are exhilarated and energized by the exercise. The next morning, Ross finds his history students sitting upright and silent in their seats when he walks in—he understands that they don’t just tolerate but actually crave the discipline he’s meting out to them, and decides to take the experiment one step further. He writes the words “STRENGTH THROUGH COMMUNITY” on the board, and urges his students to consider the fact that they can accomplish incredible things if only they work together. Ross leads the students in a recital of their class’s new motto—“Strength through discipline, strength through community”—and then introduces a logo, a name, and a salute for the movement, which he has decided to call The Wave. As the students rehearse The Wave salute, Ross is impressed—and slightly nervous.
As The Wave travels through the school, some students, like David Collins and his football buddies Brian and Eric, embrace its tenets of hard work, discipline, and community—while others, like Laurie Saunders, find The Wave a little “militaristic” and threatening to individuality. Ross wonders how far he should take the experiment, and ignores Christy’s warnings against becoming a “guinea pig” in his own laboratory. Nevertheless, Ross pushes The Wave even further, passing out membership cards and appointing certain students to be monitors tasked with reporting disobedient Wave members directly to Ross himself. He introduces a third motto—“STRENGTH THROUGH ACTION”—and encourages Wave members to recruit new members from the lower grades, too.
The social order at Gordon High begins to change—cliques break down, and even losers like Robert Billings are accepted by the more popular kids. Laurie begins feeling more and more skeptical of The Wave—though it makes everyone feel like equals, there’s something “creepy” about how unthinkingly all of her classmates are going along with it.
As the days go by, more and more students join The Wave. Ross’s senior history class is prepared, on-time, regimented, and respectful, and though Ross is overwhelmed by the spread of The Wave, he wonders if his experiment could actually revolutionize schools. As students plan a Wave rally to “indoctrinate” new members, though, Laurie tasks her Grapevine staff writers with rounding up as many stories as they can about how Gordon High students really feel about The Wave. Ben Ross is summoned to a meeting with the school’s principal, Principal Owens, who tells Ross he’s skeptical of The Wave. Ross assures Owens that the movement is nothing but a class experiment, and Owens gives Ross the go-ahead to continue on with it—but reminds him that “there are limits” to such experiments.
When Laurie discovers an anonymous letter to the Grapevine that describes the bullying tactics and threats used by members of The Wave in their recruitment of other students, she grows even more concerned. Robert Billings appoints himself Ben Ross’s “bodyguard,” and Ross, too, starts to wonder if The Wave has entered dangerous territory. As preparations for the Wave rally intensify, Laurie and David fight, and David accuses Laurie of hating The Wave because it means she’s “not special anymore.” Over the weekend, Laurie attends the football game in hopes of informing Amy of just how dangerous The Wave is—but she is forbidden from joining the member-only seating unless she performs the Wave salute.
Laurie calls an emergency meeting of the Grapevine staff, and together they assemble an issue that seeks to expose the true face of The Wave. On Monday morning, Laurie finds Amy in the halls to tell her about the paper, which will be out at lunchtime—but Amy, who has always seen Laurie as her competition, echoes David’s earlier accusations and dismisses Laurie out of hand. As the new issue of The Grapevine circulates throughout school, rumors and gossip abound—and Ben Ross, amidst his colleague’s whispers that he has “brainwashed” the entire school, begins to worry about the moral compromises he’s made for The Wave.
That night, Christy confronts Ben about the beast he has created and begs him to put a stop to it. Ben insists that the students must be pushed even further—otherwise, they’ll fall just short of learning “the most important lesson of their lives.” Meanwhile, Laurie, who leaves the Grapevine offices late after celebrating the issue with her staff, finds the word “ENEMY” written on her locker. She hurries out of the halls to find David waiting for her outside the building. He confronts her about her demonization of The Wave, but Laurie insists that she’ll write what she wants, when she wants. In a fit of anger, David grabs Laurie and throws her to the ground. He immediately realizes the gravity of what he’s done and embraces Laurie, apologizing to her profusely. Meanwhile, at home, Ben Ross works on a solution to ending The Wave the next day. When Laurie and David knock on his front door, he’s surprised, but lets them in. They beg him in earnest to stop The Wave, and he assures them he’s going to—but asks for their trust for just one more day.
The next day, Ross begs an irate Principal Owens for just a few more hours. Owens has been fielding frightened and angry calls from teachers and parents alike—and has even received a report of a Jewish boy being beaten up, allegedly by Wave members. Owens warns Ross that if the experiment isn’t over by the end of the day, Ross will lose his job. Ross accepts Owens’s condition, and heads to class to put a stop to the experiment. In history class, he announces that a special impromptu rally will be held that afternoon. He tells the class that a “National Wave Youth Movement” has begun, and the leader of the movement wants to thank the students of Gordon High for starting it. Laurie and David believe Ross has tricked them in his quest for power. Unable to bear being at school any longer, they decide to cut class. While sitting in a park, however, the angry Laurie is overcome by the need to see the “leader” of The Wave.
Laurie and David return to school just as the rally is beginning. Ross tells the entire student body—who sport Wave armbands and fly Wave banners—that The Wave’s leader will soon speak to them on the television. When the television remains blank and signal-less, however, some students accuse Ross of deceiving them, crying out that the movement has no leader. Ross exclaims that it does—and with the help of Alex and Carl, reveals a giant projector screen that bears the face of Adolf Hitler himself. Ross tells the stunned students that they would have made “good Nazis”—they followed a movement blindly, allowed others to make their decisions for them, and renounced their “individual rights” in the name of an equality that didn’t actually exist, since Wave members discriminated against non-Wave members cruelly and violently. Ross begs the students to never forget the lessons they’ve learned through this experiment.
As the stunned students file out of the auditorium, Ross apologizes personally to Laurie, David, Eric, Brian, and Amy. After they leave, the only student left in the room is Robert Billings, who sits weeping in his seat. Ross comforts Robert and offers to take him out for a meal, stating that the two of them have a lot to talk about.