The soap opera follows the story of young Aurélia Camargo (Norma Blum), a girl who falls in love with the ambitious young journalist Fernando Seixas (Cláudio Marzo), who also falls in love with her, but rejects her when he receives an invitation to marry Adelaide (Fátima Freire), the daughter of Tavares do Amaral (Felipe Wagner), a wealthy banker. Feeling abandoned by her great love, Aurélia dreams of one day having him back. Until, when she turns 18, she is surprised with an inheritance from her grandfather, and becomes a very rich woman, allowing her to create her own rules for her life. However, for the society of the time, it was not good form for a woman to enjoy such independence. For this reason, Aurélia begins to rely on a distant relative, Dona Firmina Mascarenhas (Zilka Sallaberry), to act as her mother, and on the administrator Mr. Lemos (Alberto Perez), to guide her in business. So, she sees a great opportunity to have Fernando in her life again.
When his father passes away, Estácio (Osmar Prado) and his aunt Úrsula (Ida Gomes) receive his will and are surprised to discover that most of the inheritance was left to Helena (Lúcia Alves), a previously unknown daughter. In the will, her father asks that his daughter be taken in by her relatives. The news infuriates Úrsula, who has been in charge of the family business and caring for Estácio since his mother passed away, and does not accept Helena willingly, seeing her as an intruder in the family. In addition to Úrsula, someone who is not pleased with the girl's arrival is Dr. Camargo (Rogério Fróes), father of Eugênia (Ângela Valério), Estácio's fiancée. Even so, Estácio obeys his father's request and takes the girl to live with his family. Helena has a cheerful and outgoing temperament and her arrival affects everyone's lives. At first, she is hostile to Úrsula, but later wins her sympathy.
Mundo de Juguete is a telenovela produced in Mexico by Televisa in 1974. It is a remake of telenovela Papá Corazón.
This telenovela holds the record for having the second longest run ever for a Latin American telenovela, with a total of 605 episodes. Most telenovelas run for an average of six to eight months; the shortest ones run about four months, and the longest up to a year. Many "Mundo de Juguete" fans believe that either all or some of the tapes and film from the telenovela were lost when Televisa collapsed during the 1985 earthquake. Televisa has been secretive regarding which tapes were lost during that earthquake, so there is no way of confirming this. However, such claims can be disputed, considering that the Telenovela has been repeated on television several times after 1985. During the nineties, it was repeated on Mexico City Canal 9. For a period of time, it was also shown on Unicable or on Telenovelas Televisa remade the telenovela in 2000, and called it "Carita de Angel".