Suspense Killing You?

... Trixie broke into the red trailer and found a pistol licence in Uncle Monty's coat pocket. The photo on the licence was of Uncle Monty, but the name was Tillney Britten! You'd think that would be enough, but they had a tough job convincing the police... until Mart played back a confession he had recorded on a 'spool' with a borrowed 'recording machine'.

As Uncle Monty aka Tillney Britten said, Trixie is too smart for her own good.