On Valentine's Day, a surprise marriage proposal goes awry with dangerous consequences. Athena attempts to help a desperate woman and unintentionally joins the Lonely Hearts Club. Bobby and Chimney pull holiday duty and learn about the "Casanova Fracture" and Abby and Buck go on their first official date.

Buck jumps back into the dating scene but fears he will return to his old ways; a woman goes to great extremes on a freeway overpass to get the attention of her husband; a couple have a car accident on their wedding day.

The first responders deal with a calamity at a chocolate factory; a mail bomb explosion; Eddie receives some surprising news from Shannon; Maddie contemplates her future in the call center.