Conversational agents (CAs) in narrative experiences are defined by the role they endorse and the communication style they adopt when users interact with them. In computer games, users' perception of intelligence and believability ascription influence the positive evaluation of CAs. Yet, the impact of CAs' role and communication style on users' experience remains to be clarified. In this research, the effect of the role and communication style of CAs on users' evaluation is investigated in a crime-solving textual game. Different CAs were created whose roles in the narrative (witness or suspect) and communication style (aggressive or cooperative) were manipulated. A Wizard of Oz method was used to control communication style while users' experience was assessed regarding their interaction with each CA using scales of perceived intelligence and believability. Users also had to indicate a culprit and rate the certainty of their judgments. The results show that both CAs' role and communication style have an influence on users' perception of intelligence and believability, with a higher effect of the role. However, only communication style had a significant influence on the choice of the culprit.