This article proposes an in-depth analysis of Tv show La máquina de la verdad (Tele 5). Its development addresses the uniqueness of the program, which became one of the paradigms of reality tv in the 1990s, inscribed in the collective memory and the history of the Spanish television. A sign of his hallmarks were the themes and the protagonists: current-time celebrities, controversial, with judicial implications; its staging; and the profile of its presenter, Julian Lago. The format was divided into three parts: the interrogation of a public person, who explained his version of a controversy; the discussion with guests, who questioned or supported his account; and the final outcome, which checked the veracity of the responses of the character monitored by a lie detector. This formal structure and the effective and controversial thematic content, enshrined the program as a reference for subsecuent tabloid programs.