The giant's necklace / Michael Morpurgo.

It all began with a necklace, made of glistening pink cowrie shells. A long, long necklace that had taken Cherry days weeks of careful, painstaking work. It was nearly complete, and Cherry was determined it would be the longest necklace she had ever made; that it would be fit for a giant! But the end of the holidays had arrived. "You've only got today, Cherry," said her mother. "Just today, that's all." Cherry didn't mind, a day would be enough she only needed a few more shells. So, amidst the taunts of her older brothers, she set out to search for them. Then the clouds grew dark and the waves grew large, and as the storm blew in, Cherry realized, to her horror, that she was cut off from the shore. From then on, events began to take a decidedly dark turn. One from which there was no turning back.