Lulu Tang was a baby when she diagnosed with retinoblastoma, a rare form of eye cancer. Doctors in China wanted to remove her eyes. Instead, her family moved to New York for lifesaving treatment.

Why is this violin worth $18 million? We traced the 300-year journey of this Stradivarius from the historical streets of Cremona, Italy - its birthplace - to London and New York, discovering the secrets it carries within its wooden chamber.