After talking to Gary you learn he has opened a rift. You can find the rift at the switchboard. You should enter it.
This is the low-spoiler guide for "Entering the rift at the switchboard" puzzle in The Darkside Detective - A Fumble in the Dark. Unlike in normal walkthrough, you get gradual hints on how to solve the puzzle. Click the big button below to see your first hint. If the hint contains a spoiler, you will be warned about it before clicking.