This is a short chapter inside Nathan's home. Inspect the treasures Nate has found in other adventures, last but not least the crucifix. After that, grab the toy gun and start goofing around, hitting the targets. After a short while, Elena will call you down. Feel free to check out the house, then head downstairs.
What you have to do here is quite straightforward, and there's a pretty legendary minigame coming up that will surely bring back memories for older players. Try and beat Elena's highscore - if you can, that is.