The Adventure of the Mad Tea Party - S1.E8

Ellery and his agent, Howard Biggers, travel to the estate of the wealthy and eccentric Spencer Lockridge. It seems as though Biggers wants to turn one of Ellery's books into a play and is trying to get Lockridge to provide the financial backing. All goes for naught when Lockridge disappears while wearing a Mad Hatter's costume from the Alice in Wonderland theme party he was throwing. Whodunit? Could it have been someone from New York or maybe even Dallas?