MUM is a no-dialogue film about a distraught teen and a grieving mother at the train tracks in Silicon Valley in the early hours of the morning. He runs into her along the tracks and watches her setting up a makeshift shrine for her departed son, whom he recognizes. He shares a moment of prayer with her and is overcome by his own emotions. She patiently waits for his emotions to subside and he feels compelled to share his reasons for being there. He feels she is trivializing his reason and prepares himself for the arriving train. She holds him firm as he wrestles out of her grasp to jump in front of the passing train. The moment passes. She walks towards the rising Sun. He follows.