Bobby and the 118 race to the rescue when an abandoned oil well erupts and causes a massive sinkhole in downtown LA. Athena investigates a 30-year-old cold case involving a casino robbery. Buck fears his relationship with Taylor might be ending, and Hen meets a man from her mother, Toni's, past.

Athena, Bobby and the 118 "speed" to the rescue to save a family whose pick-up truck has been rigged with a pipe bomb which will detonate if the vehicle slows under 55 miles an hour. Meanwhile, Eddie has a rough transition into his new job, Buck makes an impulsive relationship decision and the 118 welcome two new members to the team.