Thirteen-year-old Jack knows what cured his baby sister when his family thought she might never get well--Dr. Kingsbury's "Miraculous Tonic." Guaranteed to relieve maladies known to man or beast, Dr. Kingsbury's potion can cure everything from pimples to hearing loss to a broken heart, and Jack himself is a witness to the miraculous results and the doctor's kindness. When he had no money, the doctor didn't turn him away but gave him the tonic for free along with a job--to travel with him from city to city selling his cure-all elixir.

When Dr. Kingsbury and Jack arrive in Oakdale, the town at first feels like any other they've been to. But it's clear Oakdale is a town with secrets, and its citizens are slow to trust strangers.

Then Jack meets Cora, and a friendship neither expected starts to bloom. Together they uncover something else they didn't expect--not only secrets about the town but also Dr. Kingsbury. As they race to discover the truth, they'll have to decide who and what to believe before it's too late.