So you've finished BioShock Infinite, and you probably have some questions. The story is actually quite straightforward when you break it down, but some details are either left ambiguous, or hidden away in Voxophones. Here we present 19 of the game's mysteries and attempt to solve them in a digestible Q&A format. Remember, though - some of this is speculation, or our personal interpretation. You might have your own ideas...
Who are the Luteces?
The Lutece twins are, in fact, the same person. "What separates us now but a single chromosome?" asks Rosalind in a Voxophone found in Emporia. She was a physicist, and developed the technology that allows Columbia to float. During her experiments she met a male version of herself from another universe, Robert, whom she refers to as her 'brother'. Together, they're incredibly powerful, and able to travel between universes freely.
Initially, the Luteces were working for Comstock. They devised the plan to take Booker's daughter through another reality, under the pretence that he was 'selling' her to wipe away his gambling debts. But realising that Comstock's prophecy - "The Seed of the Prophet shall sit the throne and drown in flame the mountains of man" - would come true, they turned against him. Booker is pulled into their universe and given a mission: find Elizabeth and take her away from Columbia, thus preventing a future in which she accepts Comstock's philosophy and becomes a tyrant.
Who's the dead guy in the lighthouse?
After Booker is dropped off by the Luteces, he finds a dead man tied to a chair. He has a pillowcase pulled over his head, and appears to have been executed. It's clearly the work of a professional, and not just a random murder. On the floor below, a note signed 'C' is pinned to a map charting Columbia's movements: 'Be prepared. He's on his way. You must stop him.'
The note was left by Comstock. He knew Booker, the 'False Shepherd', was on his way to Columbia, and instructed the lighthouse keeper (or an assassin posing as one) to stop him reaching the rocket. But the Luteces got there first and killed him, because they didn't want him interfering with their plans. Why was he killed so violently, though? And left out on display with a sign saying 'Don't disappoint us' hung around his neck? To show Booker that his employers mean business, and not bringing them Elizabeth would have similarly gruesome consequences.
Why do we hear contemporary music in 1912 Columbia?
As you travel through the city, you often hear anachronistic music. A barbershop quartet on a flying barge singing The Beach Boys' God Only Knows (1966); an organ grinder version of Cyndi Lauper's Girls Just Wanna Have Fun (1984) on Battleship Bay's boardwalk; an old woman singing Creedence Clearwater Revival's Fortunate Son (1969) in Shantytown; a blues version of Soft Cell's Tainted Love (1981) in the Graveyard Shift bar.
The answer to this mystery can be found in Emporia, in a building called Magical Melodies. You find a body lying on the floor surrounded by instruments, clutching a Voxophone. On it, the voice of Jeremiah Fink reveals that the man, a composer he calls the 'Mozart of Columbia', has been hearing the music through the tears and copying it. Another clue can be found much earlier on the quartet's barge, on which a sign behind them reads: "Hear the music of tomorrow... today!"
How did Elizabeth get her powers?
On Monument Island you find a Voxophone recorded by Rosalind Lutece titled 'The source of her power'. "What makes the girl different?" she muses. "I suspect is has less to do with what she is, and rather more what she is not. A small part of her remains from where she came. It would seem the universe does not like its peas mixed with its porridge."
This 'small part' is Anna DeWitt's pinky finger, which is severed when she's pulled through the collapsing tear from Booker's reality to Comstock's. By being physically present in two places at once, Elizabeth is able to travel between, and open doors to, other universes. At first the full extent of her powers are stifled by the Siphon (more on that later), but when it's destroyed at the end of the game she finds herself able to open infinite doors to infinite universes.