Verdigris Deep

Verdigris Deep is a children's fantasy novel by Frances Hardinge. It concerns three children who fall into the power of a "well witch" after stealing coins from a wishing well. They are given various powers to grant the wishes of others. While many of the wishes seem harmless they all eventually lead to perilous fates. It was originally published by Macmillan in the UK in 2007 and released in the United States a year later under the title Well Witched.