When you first enter Fort Frolic you will be greeted by Sanders Cohen. If you look around the lower area of the atrium you will notice a blue tonic bottle and a chest that says Cohens muse box that is wrapped up in chains. You might be wondering, how do you open this box? The answer contains a spoiler, so if you are just arriving in Fort Frolic I would suggest finishing the story here before reading any more. You can’t access the box until you are ready to leave this area.
Assuming you have now completed this part of Bioshock, it’s time to leave Fort Frolic. Cohen will have appeared and will have opened the box with the tonic for you, but says you are not worthy to access the muse box. It’s time to kill the asshole. it’s a tough fight so be prepared. Once he is dead he will drop the key to unlock the box.
The contents of the box are very disappointing. I am unsure if the contents are random, but I found 70 dollars, 8 incendiary bolts and 3 splicer organs.