The year is 1773, and in Boston, the tensions between the colonists and the British are heating up. For twelve-year-old Silence, the tensions at home are running high as well. All she wants is a chance to call Lily--a beautiful snow-white mare--her own. But Silence's mother does not think it fitting for a young girl to spend so much time out riding and being reckless. Then, in the days leading up to the dramatic Boston Tea Party, Silence learns that someone has been taking Lily out under the cover of darkness. When the whole family is threatened by the events, Silence begins to worry that if she doesn't do something drastic, she may lose Lily forever.