Scenarios are widely used to specify desired system behavior.  In this paper, we discuss a case study of an enhanced voice messaging system, in which the scenarios describing it were assembled into a scenario network.  In a scenario network, each scenario is connected to those that may follow it.  The resulting scenario network provides a specification of the entire system.  The process of creating the scenario network improved the quality of the resulting specification by enabling us to identify gaps and inconsistencies that reviews and walkthroughs had not uncovered.  Production of a scenario network compels analysts to improve the coverage and correctness of a set of scenarios, thereby improving the requirements engineering process and the resulting documentation.