It's been quite a week for the King family--on April 24, the latest Dark Tower novel, The Wind Through the Keyhole was published and as of April 27 sits at #9 in hardcover and #21 for Kindle. But one week earlier, on April 17, King published a Kindle Single with his son Joe Hill called "Throttle," inspired by King's Duel. The e-book, which sells for $0.99 from William Morrow, is ranked #4 on the Kindle Single bestseller list, and #119 on the regular Kindle bestseller list.