It all begins when Jane finds a strange coin on a sun-warmed sidewalk. And because she and her siblings are having the worst, most dreadfully boring summer ever, she idly wishes something exciting would happen. And something does: Her wish is granted.

Or not quite. Only half her wish comes true. It turns out the coin grants wishes—but only by half, so that you must wish for twice as much as you want.

Wishing for two times something is a cinch, but other doubled wishes only cause twice as much trouble. What is half of twice a talking cat? Or to be half-again twice not-here? And how do you double your most heartfelt wish, the one you care about so much it must be perfect?