Walter H. White (Bryan Cranston), a high school chemistry teacher in New Mexico, is the only source of income for his struggling family. He has been law-abiding and conscientious for most of his life, but on his 50th birthday, he suddenly learned the bad news that he had advanced lung cancer, which made his already unsatisfactory life even worse. In order to ensure that his pregnant wife Skyler (Anna Gunn) and disabled son Walter Jr. can have food and clothing after his death, Walter decided to take risks. He took the initiative to find his former student, now a drug dealer, Jesse Pinkman (Aaron Paul) to discuss cooperation, and used his skilled and superb chemical technology to extract high-purity methamphetamine for the latter to sell. Unexpectedly, the development of the situation took a sharp turn for the worse after Pinkman brought back the drug supplier Crazy Eight and his cousin, and Walter's life was completely out of control. He was forced to start a dual life of teaching and drug making, and gradually fell into an abyss of no return.