Ghostwriter was a PBS show about a group of Brooklyn-based kids who solved neighborhood mysteries. The kids were brought together by a ghost (who looked like a tennis ball-sized glowing light) who wrote to him. They named him "Ghostwriter" because he could only communicate by reading and writing. Only his chosen kids could see him.
The kids all kept casebooks (small notebooks) and wore pens on a string around their necks to that they could write down clues to their cases at any time. The audience at home was encouraged to follow along and try to solve the cases with the Ghostwriter team. (The show was promoting literacy, but honestly as a kid I never noticed that aspect of it. It was just a cool show to watch.)
The team started out with five members: Jamal, Lenni, Tina, Alex, and Gaby. Rob was added early in the first season. The cast went through some changes, losing Rob early in season 2, gaining Hector in season 2 and Casey in season 3, and re-casting the role of Gaby in season 3.
The acting and production quality weren't great, but they weren't really issues either. If you were a fan of the show then the nostalgia factor alone should make the episodes enjoyable forever.