While in Paris, Hans's animal drawings came to the attention of a French publisher, who commissioned him to write a children's book. The result, "Cecily G. and the Nine Monkeys", is little remembered, but one of its characters, an adorably impish monkey named Curious George, was such a success that the couple considered writing a book focused entirely on him. The outbreak of World War II interrupted their work. Being Jews, the Reys decided to flee Paris before the Nazis invaded the city. Hans assembled two bicycles, and they left the city just a few hours before it fell. Among the meager possessions they brought with them was the illustrated manuscript of "Curious George".