Walter White is a high school chemistry teacher who learns that he has lung cancer. With a new lease of life, Walter sets up a mobile meth lab with a former student and becomes a drug dealer in order to secure his family's financial security.
When Skyler suspects that Walt isn't telling her the truth, she adopts a cold and businesslike approach toward him. Meanwhile, as Gus draws him closer, Jesse proves his worth to Mike and Gus' enterprise.
Walt prepares his defence against Gus, as Jesse copes by reviving his friendship with Badger and Skinny Pete. Meanwhile, as Skyler hatches a scheme of her own, her sister Marie struggles to deal with Hank's deep depression.
While Walt worries about Gus's interference and Jesse's increasingly fragile state of mind, Skyler steps up the pressure to get what she wants.