Nobody Knows (2004)

Based on a true story, a young mother secretly moves her four children into a new apartment and later abandons them to the care of the eldest, not yet a teenager. It’s an obviously heartbreaking tale and it goes on for long enough that it feels verging on tragedy porn. The film is mostly scenes of the children acting amongst themselves and this is handled delicately and naturally, letting the kids be kids even while the outside world puts very real pressures onto them.