Dependent on each other is the name given by the Shake's narrator; the actual title of the drama is "Giant," which is set in 1960s Seoul and tells the story of three siblings growing up amidst the city's great urban development.
In 1960's South Korea, Gangnam is the most powerful and promising place to develop, and all ambitious people are eager to kill off the place that will run Seoul's center of gravity in the future. Cho Baek-yeon (Jung Jewel), who is supposed to be a section chief of the Central Intelligence Agency (CIA), uses his position to seize the finances and use the money to bribe a good upper-level official in a case of smuggling gold nuggets.
But what he and his accomplice Hwang Tae-sub (Lee Deok-hwa) did during the gold grabbing incident was made known to truck driver Lee, who was killed by the combined forces of the two, and Hwang Tae-sub swore allegiance to Cho Baek-yun to save his life. But the slain Lee's family is broken up as a result.
The film is the first of its kind in the world.
Lee, who had three sons and a daughter, was killed just after his youngest son was born and his wife died of illness. The family fled to Daejeon in the chaos, but the brother was separated from his siblings.
Lee Seong-moo (Kim Soo-hyun/Park Sang-min), the eldest brother, was dramatically adopted by Cho Baek-yun, the man who killed his father. Cho Baek-yun was completely unaware that the orphan was officially a descendant of the Lee clan, but instead doted on him because of his intelligence and Lee Seong-moo grew up to become a key member of the Central Intelligence Agency.
In an accidental reunion with his grown-up second brother, Lee Kang-moo (Lee Beom-soo), and his sister, Lee Mi-joo (Hwang Jung-yeon), the three of them are reunited to marvel at their different encounters. But it was at this time that the elder brother, Lee Seong-mo, discovered that the one who killed his father was his own adoptive father, and after learning that Hwang Tae-sub also secretly wished to avenge Cho Baek-yun, Lee Seong-mo and Lee Kang-mo decided to join him in his dream of vengeance.
Jo Min-woo (Joo Sang-woo), the son of Jo Baek-yun, and Hwang Jung-yeon (Park Jin-hee), the illegitimate daughter of Hwang Tae-sub, were originally engaged to each other, but Hwang Jung-yeon, a strong woman, fell in love with her second son, Lee Gang-mo, who was carrying a heavy burden to avenge his father's death. Jo Min-woo later meets Mi-joo and falls in love with her. Despite the loss of Mi-joo, he still pines for her and searches for her due to his father's obstacles. Mi-joo, on the other hand, is a star because of her beauty and the opportunity she has been given.