When guardian angel Harry Mills arrives on Earth for the first time, he's got a lot to learn about life as a human. But this miracle worker-in-training ignores the advice of his seasoned heavenly mentor, Celeste, to eagerly take on his first assignment—helping a young woman named Addie find the confidence to change her life. Now, after her father's sudden passing, Addie is living with her mom Sharon, filled with regret and uncertainty while attempting to finish her degree all while avoiding her childhood nemesis and neighbor, Erich. Enter Harry, posing as her fumbling, well-meaning new English teacher who takes on the task of guiding her to see the wonderful things she can't see in herself. With a deadline of Christmas day to change Addie's perspective, or else say goodbye to his own Earthly existence, Harry is clueless but endearing in his effort to make Addie open up to a life full of promise—and even love—while learning a few life lessons of his own along the way.

When a family faces loneliness and loss of faith, Mrs. Miracle swoops in to renew their Christmas Spirit, and they experience a holiday of heavenly proportions.

Three adult siblings (Lamothe-Kipnes, Dowden, Lloyd-Jones) return to their childhood home at Christmas to honor their late grandmother's wishes and try to agree on new leadership for the family's company. Enter Annie Merkel (Boston) – also known as Mrs. Miracle – who poses as an estate planner and uses her special brand of Christmas magic to help the family find common ground and rekindle their bonds. As the siblings try to sort things out, Charlotte (Lamothe-Kipnes) also finds herself reconnecting with Austin (Novlan), the manor's caretaker and her first love.