Vince promises to borrow his truck if you get him a permit to set up his carnival to Twin Lakes.
You need to call the precinct.
This is the low-spoiler guide for "Permit for Vince" puzzle in The Darkside Detective. 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.