Could be a late 80s or early 90s film.
It's set in the 19th century I think, by a seaside town - a brother (about 12) and his younger sister (about 9 or 10) are homeless orphans, and they witness a murder in an alleyway, and see the shadow of the murderer - a man with a hook for a hand. They see the 'hook' man run away and a drunk man stumbles into the area, and the drunk is then suspected to be the murderer, and locked away, awaiting trial. The kids sit in a tavern and discuss with each other how they must save the drunk, as they know he is innocent, and the man with the hook is the real killer, but the real killer is sitting near them in the tavern and overhears them, knowing he has to silence them, as they are now in danger.
Eventually, the drunk man discovers the kids are his own, as he recognises something they have that belonged to his wife, and he saves their lives when the murderer goes after them. The kids then live with their dad and aren't homeless anymore.
Anyone know it? I'm positive it was a movie, and not a episode from some TV show...