“Jack and Molly were twins, and this was their ninth birthday. Such a happy, exciting day it had been; it felt like a birthday all day long, so you can guess how jolly it was, and how special it made Jack and Molly feel. Little did they guess what a weird and mysterious end to the day was now approaching!.... “Had Aunt Phœbe known when she bought ‘this useful little thing’ what it Really Was—could she have foreseen any of the mysterious happenings that were to follow the arrival of her birthday present—she would have preferred to send her niece half a dozen of the most jingly silver bangles ever made; for she disapproved of adventures in any shape or form, even more than she disapproved of bangles. Yet it was entirely through Aunt Phœbe that Jack and Molly took part in the adventure of the Grey Pumpkin at all.” - Summary excerpted from Chapter 1 of Knock Three Times!