汽车人和霸天虎连年不断的战争，给地球带来了莫大的伤害。为此，地球各国联合成立反应部队，针对变形金刚无论正邪一律绞杀。与擎天柱交往甚密的地球人凯德•伊格尔（马克·沃尔伯格 Mark Wahlberg 饰）不顾身边人的反对和政府的压力，以一己之力为大黄蜂、钢锁等汽车人提供庇护场所，期间他无意得到一枚徽章，从而将危机引向自身。失踪的擎天柱飘回赛博坦，被变形金刚的创造者昆塔沙捕获并黑化，命令他返回地球寻找至高无上的权杖，毁灭地球，复兴赛博坦。与此同时，威震天和地球政府达成协议，彼此联合追寻凯德及其盟友的踪迹，其目标同样是曾属于魔法师梅林的权杖。
　　地球真正的危机终于降临了……

　　Lois Ames is devoted to her job as the editor of a magazine, and her wealthy husband Fred is equally dedicated to polo and parties. Lois's long hours drive her secretary to quit, and she replaces her with Tom Sheridan, who happens to be in the office demonstrating a rowing machine. Tom likes the work and continues to advance until he is indispensable to Lois. Ruth Holman, Tom's fiancée, is jealous of Tom's relationship with Lois and with some reason, as he is falling in love with her. In the meantime, Fred is having an affair with Ann Le Maire, a woman whose interests are closer to his own. Because he feels his love for Lois is hopeless, Tom quits his job and plans his marriage to Ruth. Lois tries to patch things up with Fred, but he suggests that they divorce instead. On Tom's last night, Lois keeps him working late. Ruth is furious and storms up to the office where Lois and Tom are dining. She threatens to tell Lois's husband about their relationship, which leaves the way clear for Lois to announce her pending divorce. Ruth breaks off her engagement to Tom, and he immediately asks Lois to marry him.