Baseball is one of many games that involve identical starting and ending points. In order to leave the home plate, batters must strike the ball with great force, and to return to home plate, base runners must run as if their lives depend on it. Although leaving home plate is in the hands of the batter, returning to home plate is an endeavor that requires one's teammates to do well at bat. Ultimately, leaving and returning to home plate is no simple affair because it requires both skill and luck.

According to Kim Kyung-uk, What Is Baseball? is not a novel about baseball but rather a tale of revenge. The protagonist lost his younger brother 30 years ago during the brutal suppression of the Gwangju Democratic Movement. The troops sent to Gwangju to enforce martial law under the military dictatorship played dice games to determine whether their prisoners were communist partisans or not. The protagonist’s younger brother became a victim of the soldiers' cruel game. His family has trouble coping with the brother’s death and slides toward ruin. When his mother finally passes away, he vows revenge on those who caused his brother's death. Armed only with an old knife, a pair of dice, and a vial of cyanide, he goes in search of the soldier who beat his brother to death. He discovers the perpetrator in a hospital, but the soldier is brain dead as the result of an accident. Although the protagonist has dreamed of vengeance for the past 30 years, now he realizes that the time for vengeance has passed and decides to return home and live his life. It's unclear, however, where home is. Is it even possible for him to return to a normal life?

What Is Baseball? A variety of inexplicable coincidences catches the protagonist off-guard, highlighting the unexpected nature of life. The author has purposely written the entire novel in the present tense to avoid a style of exposition akin to a personal chronicle. Just like the protagonist, all of us are struggling in the seas of life, somewhere between departure and arrival. Baseball uncannily resembles life in this respect.