"It's a new plan," Tessa said airily. "I'm staying up in the tree house for twenty-four hours...." The National Telethon gives ten-year-old Tessa Fortune a wonderful opportunity to practise what she is most interested in - making money. Even better, no-one can call her greedy this time because everything she makes is for charity.
Helped by her cousins, Tessa sets up a white-elephant stall, determined that it shall be her first step on the ladder of success. But then disaster strikes. A local boy makes trouble and it looks as if all Tessa's hard work will be ruined. Unless she can come up with another idea - a way of branching out.