We meet Veronica Callahan, a very smart nurse who returns to Mercy Hospital after a year long tour of service in the Army. She's not afraid to take risks in order to save her patients, but this attitude might just cost her her job. In her personal life she's trying to make her marriage work with her high school sweetheart Mike, but when she sees the hospital new doctor it might not be that simple. Meanwhile, we meet Veronica's best friend and also nurse colleague Sonia, who thinks she finally found the man of her life and also Chloe, a rookie nurse who is learning the hard way how to be a nurse.

Veronica and her husband Mike try to rekindle their romance and move back in together, but this might not be as simple as they thought. At the hospital, Veronica and Dr.Sands try to just be friends but it's also not that easy. Meanwhile, Sonia is in love with the hunky cop Nick Valentino, who turns out to be more compatible with her than she thought. He helps her also with a Jane Doe case, while Chloe tries to help a patient everyone has already given up on.

After Veronica announces she's trying to get pregnant, to her surprise a pregnant woman and her unborn child need her help after a horrible car crash. Meanwhile, Dr. Harris, calls a meeting to determine Veronica's future at Mercy. Sonia helps a sleepwalking patient and her relationship with Valentino deepens, while Chloe goes on an ambulance and makes a discovery that will change Dr. Harris life forever.

As her affair with Dr. Sands surfaces, Veronica contemplates to come clean to her husband. Sonia gets relationship advice from a patient and questions her approach to dating, just as her boyfriend goes missing. Meanwhile, Chloe reunites with an ex-boyfriend but her plans take an unexpected turn when she learns some news.

After Veronica's affair becomes public, she and Mike reunite in a family crisis from Veronica's side. Meanwhile, Sonia is agitated when her high school rival comes to the hospital and ends up being her patient. Only to discover that the life of her rival life is not as perfect as she though. Later, things heat up between Chloe and her fireman, while Dr. Sands moves on from Veronica to another Mercy staffer.

Veronica might be pregnant but worries that maybe not even a baby can save her marriage. She needs to regain control of her life, and decides to work with Dr. Harris against any death at the Hospital. Meanwhile, Sonia helps a beauty queen when she has to accept her life-changing diagnosis. Chloe unconvers a secret her boyfriend has been keeping from her, while Dr. Sands gets more close to Dr. Jelani while organizing a "Bike to Work Friday" activity.

Veronica turns to a vetrans support group for help with her Post Traumatic stress, while struggling with her fathers rapidly deteriorating mental health. While chloe is forced to treat her most diffucult patient after Dr Harris suffers a mysterious injury.

Veronica is trilled to be back with Dr. Sands but their first official date is ruined by a robbery. Meanwhile, Chloe and Guillermo are put to the test in the fast-paced, high-stakes world of the ER after being re-assigned there by the arrogant new head of ICU. While Sonia bonds with the son of the rich elderly patient, and she begins to question the lifestyle she has settled into with Valentino.