Emergency response providers put their lives at risk to save others.

A night at an amusement park takes a deadly turn when a roller coaster malfunction leaves lives hanging in the balance; Abby reaches out to Buck; Athena and Hen respond to an unusual home invasion.

Bobby and his team respond to an emergency at a children's birthday party; the crew jumps into action after one of their own is involved in a devastating accident; Athena tries to cope with a tragedy that hits way too close to home.

Bobby and the team race to help the survivors of a deadly plane crash; Athena deals with chaos at the airport; Bobby confronts his past demons; Athena is out for revenge against teen bullies; Abby delivers an important message from a 9-1-1 caller.

On Valentine's Day, a surprise marriage proposal goes awry with dangerous consequences; Athena attempts to help a desperate woman; Bobby and Chimney pull holiday duty; Abby and Buck go on their first official date.