Sarah and Simon and No Red Paint

Here is the story of two children, Sarah and Simon, whose father is a painter, and who live with their parents and baby brother in a big room called a Studio. Their father is talented, but unacknowledged, and so the family is poor, though very happy. When the story opens, the father is painting his masterpiece. Sarah and Simon are good little helpers and spend their time doing chores and visiting their favorite place in town: the old second-hand bookshop with its kind owner. Soon the masterpiece is almost finished, except for the bit of red paint needed to complete it, and even the dealer agrees to buy it if it were finished the next day. But there is no more red paint, and no more money left with which to buy it. So Sarah and Simon set out to help their father, and to their surprise, end up reconciling their family with an estranged uncle and restoring the family fortune as well all with the help and kind solicitation of the bookshop owner...