The bigscreen adaptation of Phelps' For the Sake of Liberty: America's First Spy follows the last years of his life. In September 1776, Hale volunteered for an espionage assignment authorized by the country's first intelligence org, formed only a month earlier under George Washington's authority. Disguising himself as a Dutch merchant, Hale sneaked onto the island of Manhattan, which had been captured by the British, to assess troop movement. His true identity was revealed, however, and he was sentenced to be executed.