Da Lu De Gushi

In the spring of 1948, during the People's Liberation Army's counterattack, the enemy entrenched on Horseshoe Island attempted to fight to the death.

Underground guerrillas managed to get a map of the enemy's military facilities on the island and gave it to the grandfather of Xiao Tie, asking him to give it to the People's Liberation Army.

Xiao Tie offers to go to sea with his grandpa to complete the task.

(Source: Bilibili, translated)