Red Balloon follows the lives of four individuals who are each struggling with their own sense of deprivation and unfulfilled desires. Jo Eun-gang, a woman who appears humble and calm but harbors a burning ambition, finds herself entangled in the lives of her wealthy friend Han Ba-da and Ba-da's husband, Go Cha-won. As the lines between friendship and betrayal blur, the characters navigate complex social hierarchies, hidden jealousies, and the consequences of their secret longings. The series delves into the psychological toll of comparing one's life to others, exploring themes of infidelity, class disparity, and the desperate search for validation. As the narrative unfolds, the characters' carefully constructed facades begin to crumble, leading to explosive confrontations and life-altering decisions that force them to confront the reality of their choices and the true cost of their red balloons—the elusive dreams they chase at the expense of their integrity.