Scooby and the gang catch Lupin and turn him over to the police, but then once the car is far enough away, the cop unmasks to reveal Fujiko in disguise. She says to Lupin "where to next?" as Lupin winks at the camera before the show fades out and the credits roll.

Boom. Perfect ending to a Scooby/Lupin crossover episode, and it even leaves the door open for another one later on.

It would have been a pretty cool episode, but Lupin is a bit too overpowered to be captured by the Scooby-Gang