Box 13 - Short Assignment

On her return trip from checking  Box 13, Susie walks into the office and tells Dan that someone is following her. Soon, there is a knock at the office door. Dan says "Let's take a chance" and tells the visitor to "Come in". Susie asks "Who are you mister?" The man says "My name is George Flit. I'm a detective". Dan says "A detective, huh?" Susie says "Why he isn't any bigger than me" Flit says "But I have nerves of steel and the heart of a lion". Dan says "Oh, I see, and what brings you here, Mr. Flit?" He says "Well, why don't you open the envelope I put in Box 13?" Dan opens it and says "There's nothing written on the paper inside. How about that Flit?" He says "See how clever I am? I put that envelope in Box 13 as bait. Yes, I knew it would lead me to the person who put the ad in the Star Times newspaper. Dan says "Very clever Mr. Flit. Now that you have discovered me, what do you need? Flit says "Mr. Holiday, I'd say you're just the man for the job. I'd handle it myself, only I'm so tiny. Besides I've done mostly divorce work. Just the right height for key holes". Dan says "What about the job?" Flit says "Well, Mr. Gilbert Bolton sent me 50 dollars just to attend a party tonight. I'll split with you if you'll go to the affair in my place". Dan says "What's the catch?" Flit says "Oh, there's really no catch. The only thing Mr. Bolton said was there might be a little, um, bloodshed".