“Don’t be silly,” Blinky scolded. “They’re Irish. More to the point, the Nullhullers are such a disorderly bunch that they are attracted to order wherever they can find it. Hence the traveling in fives; hence the attraction to drawing symbols of perfect symmetry. It was only by accident that they discovered that this particular symbol struck fear into the hearts of suburban adults, who would blame attacks on humans with impure beliefs. An ingenious cover, I must admit.”

There was a nattering among the Nullhullers indicating that they were ready to act. The ten of them drew together in a loose circle, quivering in excitement, their mouths lifting open to reveal sparse, square teeth that looked like chunks of granite.

“How lucky you are,” Blinky said. “You are about to witness possibly the most vile ritual in all of trolldom.”

The Nullhullers’ squat bodies began to hitch and jiggle. Thick drool poured from their agape mouths, followed by a brown lard. A symphony of choking sounds emitted from their bodies as a plump, translucent sac began to emerge from each gaping throat. The sacs were nearly the size of a Nullhuller itself and crammed with soft objects of different shapes and colors. They squirted out of the Nullhullers’ mouths and landed upon the grass with moist splats, where they palpitated and shivered.

“We’re spending Saturday night watching trolls barf,” Tub said. “Good times, Jim. Legendary times.”

“The Nullhullers are nothing if not cunning,” Blinky said with a measure of respect. “Knowing that their weight prevents swift movement, they eject their organs for a short time—all but their hearts—making them among the most nimble of all trolls.”

Now as light and empty as pillowcases, the Nullhullers scrambled up the side of the house with the dexterity of squirrels. Beside me, Jack reached into the bramble of bike chains around his thighs and withdrew three corroded old horseshoes. He handed one to Blinky and one to ARRRGH!!!.

“I’ll schmoof the parents,” he said. “If there are siblings, grandparents, anything like that, use the horseshoes.”

“Horseshoes,” I repeated, trying to keep up. “Why horseshoes?”

“Didn’t we mention?” Blinky asked. “Ye gods, there is so much ground to cover! Nullhullers are changelings. They are here to replace a human baby with one of their wretched own. It’s an abominable practice. If left undetected, a troll changeling can grow to full adulthood under its human skin, terrorizing the world with ruinous behavior. A good deal of your world’s top CEOs and politicians are Nullhullers, I’m sorry to say. Thus we must test the family members for trollhood. The quickest way is by pressing a horseshoe to the forehead. Iron works best, but in a pinch, anything of horseshoe design will suffice.”

“Well, give me one!” I cried.