Cha Eun-jin Shin Eun-kyung is separated from her older sister Yu-jin when they were kids at an orphanage, and as she grows up she becomes a Kkangpae gangster, earning the nickname Mantis. When Yu-jin learns she has cancer, Eun-jin pleads with doctors to operate, but they refuse. The dying Yu-jin urges Eun-jin to marry as soon as possible, prompting a blind date arranged by Eun-jin’s underling Romeo, who also brings in a stylist to craft the right makeup for the encounter. The date ends in disaster, and Romeo is sent off to find someone more suitable.
In a moment of retaliation, Eun-jin smashes a car in anger, and a man rushes in to protect her but is accidentally struck by her. The man, Kang Soo-il, is simple and kind-hearted. He seems like a perfect match for Eun-jin and the two eventually marry. Yu-jin speaks about wanting children, and Eun-jin sets out to become pregnant, pressing her husband through several intimate encounters as she pursues that goal.
While Eun-jin is out at a meal with her crew, a man from a rival gang called the White Sharks approaches. He’s asked to leave after taking a drink, but he lingers, and Eun-jin’s frustration erupts in a stabbing at close range. The next day, a confrontation between Eun-jin and the White Sharks is arranged, and the showdown centers on Nan-man Kim Dong-wook. The two trade savage strikes, and Nan-man initially seems to have the upper hand after stabbing Eun-jin. As he moves in to finish her, Eun-jin dodges, Nan-man loses his balance and falls toward a cliff. He manages to climb back up and even tries to strangle Eun-jin, but she escapes and delivers a painful shot to his groin, then drives a knife into the ground near his face, refusing to kill him.
Soo-il discovers Eun-jin’s tattoo and urges her to renounce the life she leads. Around this time Eun-jin finds out she is pregnant and shares the news with Yu-jin, who sadly dies in front of her, telling Eun-jin that her baby deserves a father. Later, Romeo dies in Sherry’s arms after a brutal stabbing by five street punks. Sherry uses a public phone to inform Andy that Romeo has been stabbed, and Andy wrongly believes that Nan-man and the White Sharks were responsible and sets out to seek revenge. When Andy and his group arrive at the White Sharks’ warehouse, they find themselves heavily outnumbered. The pregnant Eun-jin steps forward to confront the gang, but a vicious assault by Nan-man leads to Eun-jin suffering a miscarriage. Nan-man then reveals that he has become a eunuch as a consequence of earlier events.
Meanwhile, Soo-il learns about the pregnancy and takes revenge on the White Sharks by dousing the gang and its leader with kerosene. As he wields a lighter, Soo-il is restrained, and the White Shark self-ignites along with dozens of others in the blaze. In the aftermath, Soo-il emerges as a co-leader alongside Eun-jin, and the two prepare to face another gang leader in a continuing cycle of hostility and power struggles.
