The Girl from Nowhere (2013)

Michel, a retired math teacher, has lived alone since his wife’s death and occupies his time writing an essay about the beliefs that shape daily life. One day he comes across Dora, a young homeless woman, who shows up injured on his doorstep, and puts her up until she recovers. Her presence brings something new to Michel’s life, but gradually the apartment becomes the site of mysterious happenings.

Source: TMDb