"Okay," I sighed, picking up the invitation that was in front of me. "How many people have RSVP'd to Katie's surprise party on Friday night?" "Out of the twenty-five people that we have invited, all of them have replied." My twin sister, Claire, informed. "That's good." Giving my sister a thoughtful look, I asked, "So, out of the twenty-five guests that were invited, how many will be able to make it to the party?" "Twenty-five." "That's good." I replied, breathing a sigh of relief. "That is extremely good." On Friday, Katie Russell, my sister's and my best friend in the entire world, will be turning eighteen years old. Katie also happens to be our twin brother, Cody's, girlfriend. Due to how much she means to us, Claire, Cody, and I wanted to do something special for Katie's eighteenth birthday. In the end, my siblings and I decided that throwing Katie a surprise party at our mansion would be perfect. "Do you think Katie suspects anything?" Claire wanted to know. "Honestly? No." I replied. "She thinks that you and I are taking her out for a birthday dinner. "Good." Claire smiled. "Let's keep it that way."