You are a private investigator, hired to trail Mr. Jones and find out where he goes every day for lunch.
You start out by following him in your car. Unfortunately, you get stuck in a traffic jam, and his car disappears.
This happens every day at a different location. It's always after the intersection of Main and Spruce, so you know he gets there, but after that he takes a different road almost every day.
You get a helicopter and try to follow him from the air. Unfortunately, there are a lot of tunnels, so you still lose him.
One day, by sheer luck, you discover his car outside of a restaurant. He isn't in the car, but it's a good sign. You stake out the restaurant for a few days, and although his car often ends up in the parking lot, you never actually see him go into the restaurant.
Then one day he stops going to that restaurant. You search around a bit and find his car in a different restaurant.
So then you start looking at the patrons of those restaurants, and find that while Mr. Jones hasn't been in either restaurant, Mrs. Blonde was in the first one, and Miss Brunette was in the second one.
From this, you determine that Mr. Jones magically transforms into Mrs. Blonde while going through a tunnel, until road construction changed the route and Mr. Jones then magically transformed into Miss Brunette over the second route.
It sounds bloody insane, but sure enough when you start looking at it, you can verify that indeed, Mr. Jones entering the tunnel on one side comes out as Miss Brunette on the other.
So just in case you were wondering what I do for a living, that's a pretty decent analogy.