Perry Mason: The Case of the Poisoned Pen (1990)

David Warner is at a mystery writer's convention. When he drops dead, an autopsy shows he has been murdered by a poison administered in a drink. Any of a dozen writers in the room could have done it. They all have motive, since he stole books from each of them.... except for the one whose wife had an affair with Warner. Fortunately, one of them gets to Perry Mason first, so we know she didn't do it, even though she winds up on trial for it. Is it too much to hope for a witness in the chair to confess?

It's a fairly good entry in the TV Movie revival of the series, starring Raymond Burr as Perry and Barbara Hale as girl Friday Della Street. Everyone else from the original show was dead. William Moses aids Perry in the investigation. The supporting cast of suspects includes Cindy Williams and Kiel Martin.

The the earlier entries, Burr faced a woman ADA in court. In this one, he does not beat a woman, but Andy Romano.