Ransom

A while after you drop off Gracie Ancelotti, Packie calls you telling you to get a picture of Gracie tied up. It seems the Ancelottis don't believe you that Gracie is tied up. This mission is a piece of cake (don't kill Gracie or one of Packie's helpers though as this can fail the mission indefinitely). Drive to the safehouse. Go up one level with the stairs and walk inside. One of Packie's helpers says that he wants a break, but Niko tells him he can't have one. You'll see Gracie Ancelotti sitting on a chair tied up. There are two ways to make her look up. Smack her when the game says so, or use a pistol and shoot her in the stomach. Bring up the phone Playboy X gave you and get a picture of Gracie looking up. If she looks back down, feel free to shoot her (don't overdo it though as few more shots can kill her, thus instantly failing the mission) or slap her again.

Send the photo to Packie, and leave. Note that after you're done the mission, you can never come back inside this apartment again.