After losing his crew in a fatal crash, legendary Rescue Swimmer, Ben Randall (Kevin Costner), is sent to teach at "A" School, an elite training program for Coast Guard Rescue Swimmers, in THE GUARDIAN. Wrestling with the loss of his crew members, he throws himself into teaching, turning the program upside down with his unorthodox training methods.

While there, he encounters a young, cocky swim champ, Jake Fischer (Ashton Kutcher), who is driven to be the best. During training, Randall helps mold Jake's character, combining his raw talent with the heart and dedication required of a Rescue Swimmer.

Upon graduation, Jake follows Randall to Kodiak, Alaska, where they face the inherent dangers of the Bering Sea. In his initial solo rescue, Jake learns firsthand from Randall, the true meaning of heroism and sacrifice.