Moe Berg was a prodigee, who graduated from high school at the tender age of sixteen and went to Princeton University. At Princeton, he studied classical and Romance languages and started for the baseball team for three years.

During his freshman year, Moe played first base on an undefeated team, and in his sophomore year, he was the starting shortstop. In his senior year, he was captain of the team, the best Princeton ever had, winning 18 straight games.

Both the New York Giants and the Brooklyn Robins (Dodgers) desired "Jewish blood" on their teams, to appeal to the large Jewish community in New York, and expressed interest in Moe. The Robins were a mediocre team, on which he would have a better chance to play, so he signed with them in 1923 and went on to be a backup catcher bouncing around from team to team before the war.

During the winter of 1932, Berg, Lefty O'Doul, and Ted Lyons, went to Japan to teach baseball seminars at Japanese universities. When the other Americans returned to the United States after their coaching assignments were over, Moe stayed behind to explore Japan, Manchuria, Shanghai, Peking, Indochina, Siam, India, Egypt, and Berlin.

With catchers hard to come by, Moe was in demand. Clark Griffith, owner of the Washington Nationals (Senators), invited him to spring training. Despite his desire to return to Japan, he stayed and played for Washington in 1933,

In November 1934 a group of All-Stars, including Babe Ruth, Lou Gehrig, Earl Averill, Charlie Gehringer, Jimmie Foxx, and Lefty Gomez, were to tour Japan playing exhibitions against a Japanese all-star team. Even though he was a mediocre, backup catcher, Moe was invited at the last minute to make the trip, probably because he knew Japan and could speak the language. When the team arrived, he gave a welcome speech in Japanese and also addressed the legislature.

Among the items Moe took with him to Japan were a 16-mm Bell and Howell movie camera and a letter from Movietone News, a New York City newsreel production company with which Berg had contracted to film the sights of his trip. While the rest of the team was playing in Omiya, Berg went to Saint Luke's Hospital one of the tallest buildings in Tokyo, and filmed the city and harbor with his movie camera. He provided American intelligence with his photos of the city in case they were of use to plan bombing raids.

Moe was signed by the Red Sox in 1935 and batted .286, as the backup catcher to HOFer Rick Ferrell. He played the most in 1937, hitting .255 in 148 times up and finally retired in 1939. In all, he spent fifteen seasons in the majors mainly because of his defensive skills and his knowledge of baseball.

After the attack on Pearl Harbor, Moe accepted a position with the Office of the Coordinator of Inter-American Affairs (OIAA) in 1942 and was stationed in South America.

In 1943, he was recruited into the Office of Strategic Services (OSS), later to become the CIA, by General William (Wild Bill) Donovan. In 1944, Moe hopped around Europe, interviewing physicists, and trying to convince several to leave Europe to come work in the United States.

Then, in December 1944, Moe posed as a German businessman in Switzerland. His job order from the OSS was to carry a shoulder-holstered pistol and assassinate Werner Heisenberg, the top scientist suspected of working on an atomic bomb (if indeed the Germans were moving ahead on the A-Bomb). Moe was to shoot him on the spot and then take cyanide to avoid capture but concluded that the Germans were nowhere close to an atomic bomb, so both men were to live another day.

Finally, while there, on orders directly from President Franklin Roosevelt, Moe persuaded Antonio Ferri, who had served as the head of the supersonic research program in Italy, to relocate to the United States and take part in our supersonic aircraft development. When he returned with Ferri in tow, FDR commented "I see that Moe Berg is still catching very well".