Hero of Washington Square (Top Secret 7), by Rose Estes, paperback Endless Quest gamebook
“YOUR LIFE IS IN DANGER!
You are pursued by a gang of cutthroat spies who will stop at nothing to gain the secret of nuclear weaponry. The mysterious green diamonds you have been entrusted with seem to hold the missing key they are after.
What will YOU do?
The perils you face are many and the choices are yours!”