Take another look at the sentence:
A dangerous stunt, Franklin flew over the steep staircase, his skateboard
landing with a loud clack-clack on the concrete below.
A dangerous stunt, a noun phrase, is right next to Franklin, an illogical target. Franklin himself isn't the dangerous stunt. Jumping the staircase on a skateboard is! Before you continue, review the rules for misplaced and dangling modifiers.
Go back to the sentence to try again.