The opening scene is a miniature lesson in this technique of expansion. First we see the concrete square tiles of the cement floor before we note the ambient noises of its surroundings. Birds chirping and dogs barking, the echoes of ready footsteps over wet pavement, the sound of an opening tap filling up the metallic frame of an unseen pail. Next comes the gentle sweep of the water over the floor, then its second one and its third before the water reaches the frame and covers it with the sheen of its ripples. There is the sound of brushing. When the disturbance of the wave settles down and the soapsuds disappear, the water becomes a clear mirror of what is seen above. We see the imperfect square of an open roof, the murky trellis of the railings before another wave of cleaning water. Now in the background begins the distant roar of an aeroplane, accompanied almost immediately by its visual arrival in the bright calm square of the water. This is the magical opening scene of Roma, which tells the heartbreaking story of a domestic worker in Mexico in the background of political strife and violence. It is also a powerful story about loss and betrayal. Now on Netflix. Highly recommended.