Una serie de muertes extrañas, aparentemente accidentales, generan suspicacias en la policía. Uno de los muertos es dueño de una editorial, y hay varios interesados en ocupar su puesto. A medida que avanza la investigación se van sumando los sospechosos. Las pistas relacionan las muertes y señalan en varias direcciones; su secretaria, el sucesor, el pretendiente de la hija, y algunos testigos circunstanciales, todos corren peligro de sufrir un posible accidente.

Although the title (which translates as "Murders in Chicago") promises a gangster story, this is more of a murder mystery that kicks off with the seemingly accidental death of a construction worker, followed shortly after by that of a noted publisher (an uneasy-looking Eduardo Fajardo). What follows is a very confusing story in which the police, a police coroner (José Campos) and a vagrant (Fernando Sánchez Polack) who witnessed Fajardo's death embark on separate inquests on what actually happened. Meanwhile, June (María Luisa Rubio), who works as a secretary for the publishing company, is under pressure by a blackmailer (Antonio Jiménez Escribano) who has pictures of her in the sack with the deceased publisher.