"When you get there, stop at this address." The nervous little man hands you a business card for a restaurant. "Ask for the catch of the day and then tuck a sawbuck into your napkin. These guys can get you the answers you need."
When you get the bill for your meal, it includes directions to a payphone. It's already ringing by the time you find it. You answer and explain your situation to the gruff voice on the other end of the line.
The Lead Investigator tests and gains a number of Clues equal to his test result.