Watch Once Upon a Time at Christmas (2017) HD Full Movie Free on SolarMovie. Watch Once Upon a Time at Christmas (2017) online free. When a serial-killer couple dressed as Santa and Mrs. Claus terrorizes a small town, a teen girl and...When a serial-killer couple dressed as Santa and Mrs. Claus terrorizes a small town, a teen girl and a young cop must solve the pattern behind the seemingly random homicides.