The story begins in 1995 in a fictitious city of São Dimas, a metropolitan region of São Paulo, which is a typical picture of society and politics. A medium-sized town, that has its main source of income from a weaving factory headed by businessman Fausto and his wife Magnólia, known to many simply as Mág, whom the city's population has real veneration. What most people don't know is that Mág, behind the veneer of false tenderness which all tend to view, hides her true nature; she is arrogant, authoritarian, always thirsty for power and without any scruples. By using various tricks to get what she wants no matter who gets hurt and trying to use these as justification that everything she does is to keep his family together. Fausto married Mág shortly after her first wife's death, who was Pedro's mother. They have to other children Hércules and Vitória. Pedro meets Heloísa, a young woman who lives a quiet life with her parents; her mother Cândida, who has leukemia, and the unemployed and alcoholic father Jorge. In an act of desperation, her father tries to rob the textile company owned by Fausto but ends up being indicted and arrested; in prison, there is a rebellion and the latter dies. Later, his mother also passes on from her disease for lack of proper treatment. With Helô and Pedro's relationship, which started prior to the unfortunate events, Mág and Fausto cultivate a plan to separate the two. They hire Gabriela, a new secretary of Mág to seduce and lure Pedro to bed and they also contract Helô to a modeling agency run by Mág's trusted friend and confidante Gigi. In cahoots with Mág, Gigi sends Helô away from São Dimas for a modeling leaving Pedro vulnerable to Suzana. At the same time they cut communication between the two and Pedro felt that Helô had moved on without him. On the night of Helô surprise return, Pedro got drunk and fell a sleep. Mág demands Suzana to seduce Pedro. Helô finds the naked Suzana with Pedro and believes that Pedro betrayed. During the anger episode Helô leaves São Dimas indefinitely to be a professional model where she meets Tião, a man that she marries and Pedro lives for France due to the pain he felt by Helô's absence. Years later, Helô has seemingly moved on with her powerful Tião who are apparently become distant over the years, with their two children; Letícia who suffers the same ailment the grandmother had and Edu who has a difficult relationship with his father. Pedro returns to São Dimas and their romance with Helô is rekindled, once more putting each other to the test as the forces that are set to separate them are more reinforced.
The first episode of A Lei do Amor registered a viewership rating of 30 points in Greater São Paulo, the lowest viewership for the 8/9 pm telenovela premiere.
