At a school benefit sale, Pete Hollister buys an old book about early New York tunnels.
Pete, who has been trying out a new detective kit, tests the letter for possible invisible ink and is rewarded when.
The only English word in it is "Help " The Hollisters take the mysterious note to a Chinese friend for translation and learn that the letter was written many years earlier in China by a Yuen Foo to his son in New York, but was never mailed.
Tucked in the pages is a message written in Chinese.
At a school benefit sale, Pete Hollister buys an old book about early New York tunnels