The Changeling (The Adventures of the Elderly Sherlock Holmes, Episode 20)

When Alice tells Holmes that an abandoned baby has been found in a wooded area in Greenwich, and this was already the second incident of this kind within a few weeks, Holmes, Watson and naturally Alice decide straightaway to get to the bottom of the matter. The trail leads them to the nearby workhouse. After initial conversations with the residents, the case becomes quickly clear to Holmes. And Alice knows what she must do as well...