On one of the hottest days of the year, the first responders feel the pressure as harrowing incidents keep happening around the city, including a road rage accident involving a van full of tourists, an emergency at an auto-repair shop and a veteran with a live grenade embedded in his leg. Meanwhile, Buck gets a surprise visit from his sister, Maddie. Also, Athena questions her relationship with Bobby. Then, at the fire station, handsome new hire Eddie jeopardizes Buck's chances of being chosen for a fireman calendar.