Students Hayley and James are young and in love. After saying goodbye for Christmas at a London train station, they both make the same mad split-second decision to swap trains and surprise each other. Passing each other in the station, they are completely unaware that they have just swapped Christmases.
Follows the story of the challenging relationship between Billie and her younger schizophrenic sister, Elizabeth Baby. After their mother dies, Billie takes responsibility by moving Baby in with her family, including her husband, their teenage son and young daughter. At first, Baby and the family work to adjust to their new living arrangement. However, after a disturbing incident involving her son and Baby, it becomes clear to Billie that she and her family are not equipped to handle Baby's illness, ultimately forcing her to make the difficult decision to do what's best for her sister and her family.