"Mama" follows three different families all dealing with different issues affecting their mothers. Dong-Sook (Uhm Jung-Hwa) is a single mother who works as a saleswoman for yogurt drinks and also works cleans apartments to make ends meet. Her world revolves around her son Won-Jae (Lee Hyung-Suk), who is afflicted with a disease that prevents him from walking. One day, Dong-Sook is diagnosed with cancer and her world comes crashing down. Eun-Sung (Ryu Hyun-Kyung) has always lived under the shadows of her famous opera singer mother Hee-Kyung (Jeon Su-Kyeong). Even as a married mother, Eun-Sung still at times feels like an assistant to her mother rather than a daughter. Eun-Sung's dreamed as a child of becoming a pop-singer, but her uppity mother would have none of that. As an adult can Eun-Sung achieve her dream? Seung-Chul (Yu Hae-Jin) is a mafia boss feared by his subordinates and rivals. When Seung-Chul visits his mother Ok-Joo (Kim Hae-Sook) he morphs into another person entirely. Seung-Chul worries about his mother and attempts to do anything to make sure she is happy. He also sometimes acts as a figure father to his widowed mother. When Ok-Joo learns she has breast cancer and is resistant to having a mastectomy, Seung-Chul attempts to persuade her to have the surgery. He asks his mother if there is anything she wants, Ok-Joo shows Seung-Chul an old photo herself and a man from her teenage years. She wants to meet that man one more time.