For various reasons, all three of the adult Brenner brothers currently live with their single mother, Barbara, in the family home. Stephan lives in the granny suite in her back yard as a place to hide out, he an animal therapist in believing animals more reliable than people in he being anxious around his human counterparts, especially in crowds. Taylor, a video game engineer, lives in the basement as the irresponsible, disruptive one who always manages to sabotage good things in his life. And firefighter Luke, who lives in the main part of the house, is only there temporarily while he builds his own house, that temporary status so far being ten months and running as he is easily distracted in working on one other project or another for other people. Barbara's goal is for them and their Aunt Louise to spend Christmas together, despite the brothers having pulled away from each other ever since their father abandoned them when they were children, they not even usually decorating her house for her. With five days until Christmas, someone leaves a baby named Thomas at the firehouse specifically for Luke, probably the mother who, as per the note pinned to Thomas, only implores him to look after Thomas until Christmas when she promises to come back for him. Including being certain that Thomas isn't his son, Luke doesn't know who the mother is or why she chose him as Thomas' temporary caregiver. Asking for advice on what to do, he decides to look after Thomas with Barbara's help until Christmas, and if the mother doesn't return by then, he will take Thomas to family services. As Barbara is called away shortly thereafter on an emergency, the three brothers need to care for Thomas on their own, something they are ill-equipped to do. But with Thomas in their lives, they are forced to examine their interrelationships, including the underlying issues of why the way they are as individuals who have never really appreciated self-sacrificing Barbara.
