Jason experiences success during a training exercise with the often lifeguards, able to find "the path of least resistance" - being underwater instead of swimming with his head over water. J.D.'s inventions pay off, as he performs a daring underwater rescue. Jessie and Allie become parents for a day after they come across a boy who has lost his mommy. Also, Dawn deals with a painful memory of a life and death choice from her past, as a lawsuit comes her way. Sean promises to fix the mess she's in, and he's able to do so pretty easy. They all get to know that J.D. and Dawn knew each other from the past, which makes the relationship between J.D. and Jessie even more complicated.