It's an anthology series in which each episode begins with the accused in a courtroom. Viewers don't yet know the nature of his crime, and the outcome of the trial remains a mystery. The plot, told from the point of view of the accused, depicts how an average person finds himself caught up in a cycle of regrettable decisions, until the point of no return is reached. In this context, "spiral" means a self-perpetuating cycle or series of events, making it difficult to stop or change direction.