[Just as Naruhodou explains, Sherlock's fingers begin to turn the gears. The clicking is particularly satisfying and he doesn't even know why. He just knows that it is.]

This is delightful! So simple in its nature, yet so very captivating! I'll make good use of this. Then... [He trails off for a moment, then hops to his feet.] Yes! Right! Your gift! I have one, of course. It's very well hidden so you could not stumble upon it by accident. So it must be... Hm... Upstairs! One moment!

[He sprints from the room without further delay and a second later, his feet can be heard pounding up the stairs.]