Book excerpt: Samantha's birthday party is nearly ruined when Eddie Ryland plays a mean trick. Then Agnes and Agatha, Cornelia's ten-year-old twin sisters, save the day with an invitation to visit New York City. Samantha loves the twins? carefree attitude and can't wait to go - specially since the trip will include a stop at a fancy ice cream parlor. But when the girls carelessly break some rules, they suddenly find themselves racing dangerously through the big city - and the path they take leads to surprising discoveries