A girl rushes through the streets of Delft. She has important packages to deliver: letters, guitar strings, precious earrings... and a piece of blue stone called lapis lazuli. It’s for master painter Johannes Vermeer, who will use it to make a deep blue called ultramarine. It’s incredibly expensive, worth more than gold. For an instant, the girl wonders: her brothers and sisters are hungry, maybe she should sell the stone instead...? But after she knocks on Vermeer’s door, he makes her an offer she finds hard to turn down.