"Guessing Game" tells the story of a division commander of the National Army who held Yunshanling in 1941 and was sent to the rear due to war injuries. His adjutant secretly colluded with the Japanese army, falsely passed on oral instructions, and planned a rebellion. Thirty officers refused to be humiliated and prepared a plan to kill traitors with the help of the Communists, codenamed Iron Fist. Unexpectedly, the news leaked and 28 people were killed. Underground Party Staff Officer Tong and the Guard Captain were the two surviving "Iron Fists". The two knew each other but did not know each other's identity. They fulfilled their respective missions while struggling to find each other. After many twists and turns, they found each other. In the situation of isolation and helplessness, they transformed a bandit into a military work team, and finally got rid of the traitors and crushed the betrayal conspiracy.