Meet the dysfunctional Gallagher family. The dad, Frank Gallagher is a drunk and the mother has abandoned her own family. It is up to older sister Fiona to take care the rest of the family, along with the help of the fellow neighbors Kev and Veronica. Fiona would have to deal with their little sibling's situations at school and even in the community such as Debbie stealing a baby from the neighborhood, Carl getting in trouble from his unacceptable behaviors at school, etc. On the other hand, Lip and Ian would know how to handle their own situations. For example, Lip is trying to have a relationship with his best friend, Karen but it seems that she does not feel the way Lip feels about her. And Ian is trying to date a guy named Kash who work together at a mini market. The problem with Kash is that he has a wife and two children. Fiona is also having a complicated relationship with a guy named Steve. She has trust issues with him because he is always out on his own doing his thing that is kept secretly to himself. And lastly, Frank just got kicked out of the house by his own kids because he kept doing crazy things such as abusing Ian and having him come home drunk. He is now living with Sheila, who is a lonely woman living with her daughter, Karen.
Summer is finally here! But things are a little bit different. Jimmy, also known as Steve, has left the Gallaghers to go to South America so that he can get away from the police because back in Chicago, he was stealing cars. So now Fiona is on her own. She found a new job as a bartender, and she is also trying to move on with her life and relationship. Debbie and Carl has started a babysitting service at the house to earn money. Kev and V are taking care of their foster child, Ethel. Lip is trying to get Karen back, since she has found a new boyfriend. While Ian and Kash are together, he finds another interest with Mickey Milkovich, who is his best friend's, Mandy, brother. Later in the season, Jimmy returns to Chicago with his wife from Brazil, Estefania. He has been figuring out that Estefania is cheating on him but Jimmy doesn't feel hurt because he doesn't feel anything to Estefania as he did to Fiona. Lastly, Frank steals money from Sheila.
Jimmy moves into the Gallagher's house, living a refreshed happy life with Fiona after breaking up with Estefania. Unfortunately, he is in trouble with Estefania's father who is a drug landlord in Brazil. He is getting Jimmy into danger dealing with murder and crime. So there is no escape no matter what he tries to do. Fiona is trying to have a new start with Jimmy even though she has no clue about him being in danger. Mandy starts to spend more time at the Gallagher's because of what had happened with her and her father. It is also because she is having a weird relationship with Lip. Since Ian has been going to a club, he finds some interest in guys from there. And one of them would Jimmy's father! So he has to get himself out of that relationship without Jimmy knowing about it. Debs is dealing with teenagers her age at public places. So she is learning the teenager stage. Frank is still desperate for money like always. One of his crazy ideas in earning would be telling Carl that he has cancer so that he can get the rewards and promotions so that it can also go straight to Frank. That does not work. Instead it leads to Carl going off to summer camp. Lastly, with Kev and V, Kev's ex-wife comes into town with her son. She tells Kev that her son may be his. As V starts to see what they have been developing, she starts to get jealous.
As Fiona is moving on, she meets a new guy named Mike, who is her boss at her new job. He is a calm and nice guy to Fiona and the rest of her siblings. Frank is really ill from his drinking, that his liver has rot. Nobody wants to help him except Carl. He tries to get medicine to get him better. Lip is off to college, and it is hard for him to keep up because he has not been caring about his college education. He is on the verge in getting out that he breaks rules such as destroying his professor's car, being late and even not attending his classes, etc. Ian has been absent in the Gallagher family since he joined the military. But he has not been giving updates to his brothers or sisters. With Debbie, she is going through the teenage stage with her friends. She even gets a boyfriend that is about 6 years older than her. As they start to hang out more, they develop a friendly relationship instead of a romance which makes Debs disapointed. Lastly, there is another "Gallagher" member in the family who's name is Sammi. Before Frank was with Monica, he was with another girl, who was Sammi's mom. When Sammi and Frank meet for the first time, Sammi becomes a huge help to Frank. She even starts living with the Gallagher's along with her son, Chuckie. The Gallagher's start to have an issue with her since she is invading the family and helping Frank.