A year after dispatcher Donna Majoros took the 911 call before her mother passed, she leans on her best friend, Melinda, more than ever; Abby answers a call from an address connected to Donna, and her day goes from bad to worse.

Dispatcher Savannah Brown settles in at CVD thanks to the support from her police officer spouse, but while helping callers in threatening situations with little information to relay to police, she fears she is sending them blindly into danger.

With only 24 hours to go before Memorial Day finally ends, Charline and the team's determination is put to the ultimate test after days of life-and-death emergencies; it all comes to a head when an officer chasing a suspect goes silent.