There were three clues on the “dead” agent's body about locations the agent had visited before being killed. Each team received one starting clue (so that teams wouldn't just be following each other around).
At each location they visited, agents got two new clues: a hint to the next location, and part of the description of the microfilm site.
If you had been on Team #2, for example, you would have heard the following when calling from a proper payphone.
A suspicious loiterer here identifies himself as a fellow agent and imparts the following information:
This message was found on the person of an apprehended conspirator:Make each excursion triple mental energy. A timer began each time. Hear everyone's story— don't acknowledge evil, rebellious, or lecherous smiles.
The apprehended conspirator kept repeating “Lower level, lower level” under interrogation.
Taking just the first letter of each word in the message reveals the coded instruction “MEET ME AT BETHESDA EROLS”.
Lower level is part of the microfilm site description.
The clerk behind the counter remembers the man you describe, because he asked for a very strange movie: Behind the Sign. You find the movie on the shelf and open it up. Five scraps of paper fall to the ground:
an A, a J, a 7, an L, and a W (or is it an M?)
Putting the scraps of paper in the correct order gives WJLA 7 (the local ABC TV affiliate).
Behind the sign is also part of the microfilm site description.
A man answering your description came in yesterday with what he said was “a hot news item about Hedera Helix”. He also wanted to know if there was a post office nearby where he could mail this postcard:
Hi! Having a great time! Saw the Hope Diamond yesterday, & have a lot of discoveries left to be made. Love, X
Mention of the Hope Diamond should lead agents to the Smithsonian Natural History Museum. Of course, there are numerous payphones in the museum—the team had to use one next to the Discovery Room.
Hedera Helix is also part of the microfilm site description.
Smithsonian Natural History Museum
The Lost & Found department gives you a book reservation slip for Mr. C.X. Lyon, with the inscription LC/LH&G written on it.
Washingtonians should recognize LC as referring to the Library of Congress, and a little digging will lead to the Local History & Genealogy room.
C.X. Lyon is part of the microfilm site description.
Library of Congress
The Information Desk remembers the man you describe, since he was asking about two people who lived where is staying: Thomas Sheraton of Connecticut and Nathan Hale. He said he was doing research on their involvement with English Ivy.
There's only one Sheraton on Connecticut Avenue in DC, and agents had to call from the phones near the Nathan Hale room.
English ivy is part of the microfilm site description.
The registrar at the Sheraton tells you that a man answering the description you give did check in four days ago, under the name Mr. Zalophus Californianus.
Zalophus Californianus is part of the microfilm site description.
There are no more locations to explore—agents now have all the information needed to find the hidden microfilm.
Two clues—“Zalophus Californianus” and “C.X. Lyon”—should suggest to agents that they need to find a sea lion. Naturally, that can only be at the National Zoo.
Once at the “lower level” of the sea lion enclosure at the Zoo, agents needed to look “behind the sign”, where a 35mm film canister was carefully hidden amongst the “english ivy” (AKA “hedera helix”).
The agent who returned to base with the microfilm won the Hunt!