When David Castellano receives a mysterious blue pendant on his 15th birthday, he has no idea who sent it, or what it is supposed to mean. Is this a strange prank? Or the first clue to a puzzle of epic proportions?

After a particularly stressful day at Pensatucket High School, David is surprised to find his older sister Meghan waiting excitedly for him in the parking lot. Estranged for years from their mother, Joana, since the death of their father, Meghan hasn’t been home since she started college.

But today, she says, she has a surprise. Together they drive back to David’s house, where - unbeknownst to him - his best friends are waiting to celebrate his birthday. As Meghan leads David up the front path, they almost miss the inconspicuous package lying on the doorstep. Who delivered it? And why?

Urged on by his friends, David opens the parcel to reveal a large blue pendant on a silver necklace. With no note attached and no messenger in sight, the gift is unusual, to say the least. On top of that, the blue stone in the setting begins to glow, and as the days pass - it grows brighter and brighter...

Enlisting the help of his sister, friends, and their eccentric Aunt Noelia - a historian and specialist in artifacts and rarities - David sets out to discover the meaning of the strange blue pendant. Little do the inquisitive gang know that what they find will change all their lives forever and test the limits of David’s courage, resilience and strength.