The 5,000 Fingers of Dr. T (1953)

Young Bart Collins lives with his widowed mother Heloise. The major blight on Bart's existence is the hated piano lessons he is forced to endure under the tutelage of the autocratic Dr. Terwilliker. Bart feels that his mother has fallen under Terwilliker's sinister influence, and gripes to visiting plumber August Zabladowski, without much result. While grimly hammering away at his lessons, Bart dozes off and enters a fantastical musical dream.