Set against the backdrop of Seoul's economic boom during the 1970s and 1980s, 'Giant' chronicles the epic and tumultuous lives of three siblings—Lee Kang-mo, Lee Sung-mo, and Lee Mi-joo—whose family is torn apart by tragedy and greed. After their father is murdered and their mother dies, the young siblings are separated, each forced to navigate a harsh world alone. As they grow into adulthood, they reunite with a singular, driving purpose: to seek revenge against the ruthless men—Jo Pil-yeon and Hwang Tae-sub—who destroyed their family, while simultaneously building massive business empires in the booming real estate and construction sectors.