Park Ranger Pete wanders off while leading a group of young campers, and turns up the next morning battered, bruised, and with absolutely no memory of what happened to him. While examining Ranger Pete, Hank he discovers a series of symptoms that lead to one very surprising conclusion: Pete has been struck by lightning.
Pete's accident only confirms Evan's fears about the coming End of Summer Storm, but while he focuses on emergency preparedness and battening down the hatches, the rest of the HankMed team carries on with business as usual. As Divya tries to figure out what's ailing storm-chaser Stacy, a new HankMed patient with a propensity for broken bones, Hank and Jill make their way to a catch-up dinner. But when Hank gets an alarming call from Pete, he and Jill reverse course and head for the park, despite the impending storm. With help from Stacy, whom they encounter setting up her weather-tracking device, they search for Pete. But will they be able to find him before it's too late -- or before this wild summer storm wreaks any more havoc?