In his low-key way, the German director Christian Petzold has put together a remarkable filmography — and his new movie, “Miroirs No. 3,” is among his oddest and most compelling visions yet. In “Miroirs,” which opens in New York and Los Angeles March 20 after playing Cannes’ Directors’ Fortnight last year, the actress Paula Beer plays Laura, a talented pianist who experiences a terrifying car wreck in the German countryside and is taken in by a family of bystanders. Slowly, Laura comes to realize that her hosts are treating her as a surrogate for the daughter they lost, and must...