Bei einer U-Boot-Probefahrt geraten zwei Menschen in Lebensgefahr. Allie, Nick und Sean fangen ihr SOS auf und eilen zu Hilfe. Weil den Eingeschlossenen langsam der Sauerstoff ausgeht, schließt Nick seine Sauerstoffflasche an. Das zwingt ihn, ohne Dekompressionsstops aufzutauchen. Lebensgefährlich verletzt kommt er an der Oberfläche an.
An experimental submarine and its passengers ends up in a devastating tragedy for Allie, who finds & loses love all too quickly. She finally learns to trust Nick, a rescue swimmer working at the U.S. Coast Guard; a man she's been into for two weeks. Nick takes some huge risks when trying to save the passengers in the submarine, which unfortunately leads to him getting a severe case of the bends. He never wakes up, and Allie is devastated. Mitch arranges a lifeguard memorial service for Nick. Mitch tells her "Nick wasn't a lifeguard, but he died being one."
La relación de Allie con Nick comienza a calentarse, especialmente después de que él sugiere un compromiso entre ellos. Luego, las cosas toman un giro cuando Allie, Nick y el resto del equipo deben cooperar con la Guardia Costera para rescatar a dos personas atrapadas en un submarino averiado a 200 pies en el fondo del océano.
Durante il soccorso dei passeggeri di un sottomarino sperimentale, Nick rischia la vita per fornire loro ossigeno e riemerge senza rispettare la decompressione, con conseguenze tragiche.
