Following the personal and professional lives of the heavy-water lifeguards who patrol and protect the North Shore of O’ahu, Captain Harlan “Sonny” Jennings (Robbie Magasiva) and his core team of lifeguards —lieutenant Em Wright (Arielle Kebbel), and veteran lifeguards Will Ready (Adam Demos) and Laka Hanohano (Kekoa Kekumano) monitor the most famous and dangerous stretch of coastline in the world. In the series premiere episode two rookie lifeguards, Hina Alexander (Zoe Cipres) and Kainalu Emerson (Alex Aiono) try out for a position on the team, as Sonny and his family are still grieving the loss of his nephew Zion and a romantic past is revealed between Em and a now engaged Will.
When a flash flood sweeps a young tourist away from her family and out to deep sea, Sonny, Em, and Will race into action to save her. Going against Sonny’s wishes, Em takes a bold risk, placing her own life in danger. Laka supervises rookies Kainalu and Hina’s first day on the job.
Em works to earn the team’s respect when she is left in charge. Hina and Kainalu juggle multiple beachside emergencies. Will’s fiancé pays him a visit at work. Sonny opens up to a former lifeguard about his trauma since losing his nephew. Laka continues his flirtation with EMT Jenn (guest star Sea Shimooka).
The lifeguards of the North Shore experience the most dangerous ocean conditions the district has seen in years. Sonny assigns Laka as acting lieutenant as Em has the day off and joins Jenn to catch some massive waves. Meanwhile, Kainalu's father pressures him to leave his shift and help him with his campaign over patrolling the beaches. Hina thinks she is ready to back-up the rescue skis, and Laka and Will almost make it through the day when a fight breaks out among locals. Emotions reach a boiling point for Sonny when he experiences another loss.
Sonny, Em, Will and Laka race to the beach to find missing paragliders that plummeted into the ocean by a violent down draft. Kainalu invites Hina to a party with his ex-girlfriend and pretentious high school friends. Jenn doesn’t think Laka is serious enough for her, and Em and Will face temptation of rekindling their past romance. Meanwhile, Sonny secretly puts in his notice to retire and recommends Em as his replacement.
