Fifteen-year-old Garnet Walcott is lonely and has a hard time making new friends when she moves to Kitchener, Ontario. Her mother, already preoccupied with work, has begun a search for a father she never knew. By chance, Garnet meets and befriends Elizabeth Tate, an elderly widow who tells Garnet that a priceless set of heirloom jewels dating back to Russian nobility may be hidden in her Victorian home. Elizabeth shows Garnet an intriguing portrait of her late mother-in-law, Sofia Tate, wearing sapphires and diamonds.

Garnet is introduced to Dan Peters, one of the most popular boys at school, and when Elizabeth suffers a heart attack, Garnet persuades him to help her find the jewels for Elizabeth. Do the jewels really exist? Garnet believes they do, and drawing on that faith, she follows the clues left by Elizabeth's late eccentric, religious father-in-law and discovers much more than she bargained for.