He is in the air vents of the robot club.
The inventor goes near Holmes (underground), so when you see pst... in here! or something like that,that's where the inventor is (this is main street for your information in poptropica).
The door code when chasing the inventor is 2014.
we wear it to look for the inventor
There is a window outside the building. It's hard to get to, though.
Go through a window outside of the club.
Go to the disco place, when you walk in go to items and use heat vision goggles. look strait up and he will be in the vents.
You do the window puzzle
He go's up the vent and into the attic .You need to goo outside and use the tools to break the bars on the window and go into the attic.
When you complete all the game shows Holmes will tell all the robots to look for you. You walk into town and run to the manhole and jump down where you will find the inventor guy waiting.
game show island
go on to you tube for walk throughs. type in poptropica cheats, game show island. good luck!
you go back to main street and go underground where the inventor is