The storm had intensified by the time Booker reached the double doors of the lighthouse. One door was slightly ajar, a faint light peeking through the opening. Booker gave the door three sturdy knocks. After waiting in vain for a response, he pushed the door open and went inside.

Booker surveyed the scene. The lighthouse keeper was apparently a devout man, as evidenced by the various framed quotes from the Bible scattered around the first floor. At least Booker assumed they were quotes from the Bible. He had not been a religious man even before becoming a scientist, having witnessed too many injustices to believe in a benevolent God.

As he began walking up the stairs to the second level he called out, "Is anyone there? Hello!" not expecting and not receiving a response. He wondered why the Luteces had brought him here. Since his destination was a city in the sky he had expected to be dropped off at an airfield or perhaps a zeppelin dock.

The second floor was some sort of office. Occupying one wall was a map of the United States dotted with pushpins illustrating what appeared to be some sort of travel schedule. A table of times and dates next to the map confirmed this theory. There was a note pinned to the map. It read:

Be prepared.
He's on his way.
You must stop him.

-C

A sense of unease washed over Booker. He scanned the room more carefully and noticed a cigar butt on the floor. Lucky Strike. It was warm to the touch.

The creak of an old floorboard gave away the assailant as he rushed out from his cover behind a filing cabinet, brandishing a wrench. In one fluid motion indicative of a lifetime of experience, Booker turned, drew his pistol, cocked it, and fired a round into the man's forehead. The man staggered forward another half-step before dropping to the floor with a heavy thud.

After confirming the man was dead, Booker rifled through his pockets. While there was nothing but lint in the man's pants pockets, his left jacket pocket contained a book: Prophet: The Life and Times of Zachary Hale Comstock by Edward Gaines. Booker commandeered it for later reading. Any information on Comstock should prove useful.

Booker theorized the assailant was the lighthouse keeper since the note from the mysterious "C", which Booker assumed stood for "Comstock", had been pinned to the wall as a reminder to him. An ashtray on a nearby desk filled with Lucky Strike butts corroborated his theory. But how did Comstock know Booker was on his way? Did the Luteces sell him out? Was this part of their experiment?

As he carefully analyzed the contents of the room, studying each document in each desk and filing cabinet drawer, Booker discovered the lighthouse was indeed a point of entry to Columbia. Every document he found concerned immigration. From the names on the immigration logs, it appeared Columbia was popular with the upper crust of society. Several familiar names caught his eye: John Jacob Astor IV, John Pierpont Morgan, fellow cavalryman Theodore Roosevelt.

Satisfied with the thoroughness of his search but thoroughly unsatisfied with the dearth of meaningful answers it produced, Booker began climbing the stairs to the third floor, pistol drawn.

The third floor was empty except for a naked light bulb, a chair, and some unremarkable books. It appeared to be a makeshift library. Booker continued up the stairs, which now led to the roof. As Booker reached the roof he expected to find an airship dock but was greeted only by the forlorn lighthouse lamp. He was about to go back down to the third floor, assuming he had missed something, when he noticed the three unusually decorated bells on the door leading into the lamp room. A scroll, key, and sword respectively were carved into the bells. Booker tried ringing each bell to no result. He figured it was a signaling mechanism of some sort, but what was the correct sequence of bell-rings?

If the correct sequence was 4 arbitrary bell-rings, then there were 3^4 = 81 possible sequences. He could brute-force that. Even if the sequence was 6 arbitrary bell-rings that was still a manageable 3^6 = 729 possible sequences. But if the sequence was longer than 6 bell-rings brute-forcing the correct sequence would take an impractical amount of time.

Booker realized he could potentially cut down the search space with a constraint. From the layout of the bells he theorized it was likely that the leftmost bell would be rung some number of times, followed by the middle bell, then the rightmost bell. Perhaps each bell corresponded to a numerical digit. For example, the code 123 would be represented by ringing the leftmost bell once, the middle bell twice, and the rightmost bell three times. If this theory was correct, he could brute-force check all possible sequences (9^3 = 729) in a reasonable amount of time.

Booker then considered the fact that this lighthouse apparently served as a busy transport hub for wealthy passengers. He imagined John Jacob Astor IV would not appreciate standing around while the lighthouse keeper went through a prolonged sequence of bell-ringing. As a result it was unlikely for the code to be too complex-such as requiring more than 3 rings of any bell. So he would try those 3^3 = 27 sequences first. If that failed he would fall back to his theory about each bell representing a numerical digit. If neither method worked he would default to naive brute-forcing while making plans to ambush whomever Comstock eventually sent to check on the lighthouse keeper.

Booker prepared for a long night of bell ringing.

Left, Center, Right. Nothing.

Left, Center, Right, Right. Nothing.

Left, Center, Right, Right, Right. Nothing.

Left, Center, Center, Right. Nothing.

Left, Center, Center, Right, Right. Jackpot.