Aside from a couple sloppy mistakes, "Mrs. Parker's Revenge" is an enjoyable story. It's also the penultimate TV episode of "Murder, She Wrote"...though they also went on to make four "Murder, She Wrote" movies.
Jessica is the keynote speaker at a conference for mystery writers. However, as you'd expect, she also has time for solving a murder AND stopping a terrorist from destroying millions...if not the world!
The plot here is pretty crazy compared to other episodes, as usually there is just a murder or two to solve. Here, however, it's a couple murders AND an assassin who is trying to guy up a virus that will destroy mankind. It is very enjoyable and worth seeing.
Now as for the mistakes, there were two that I noticed. First, a guy is given an envelope that supposedly contains $100,000 in $100s. But the stack is about a half an inch high...at most. Such a stuck would actually be very thick...at 4.3 inches! Second, Jessica is left a cassette by one of the murder victims. You see CLEARLY it's a cassette. But when she plays it, she plays it in a microcassette player!