"Shades of Gray" is a pathetic excuse for an episode for "Star Trek: The Next Generation"--one that insults the audience's intelligence and just looks like a lazy attempt to fill the time slot. It is so bad and so irrelevant that I recommend you skip it completely--you really don't need to bother with this one.
When the episode begins, Riker's leg is injured while on an away team mission. However, this is no mere scratch--the thing festers and cannot be eliminated using the transporter's bio-filters. Soon, Riker is dying and Dr. Pulaski is fighting to save his life.
This doesn't sound that bad, does it? Well, no...the concept isn't bad. However, this only takes up a tiny fraction of the show. Most of it consists of clips of Riker from other episodes--and they appear to be completely random in how they are used. Relevant or not--they are tossed into "Shades of Gray" and the sum effect is a show that obviously no one gave a crap about when they made it. A complete waste of time and the worst simply because there have been episodes with dumber premises (such as the baseball game episode from "Deep Space 9"), but at least they TRIED something different with these shows. Here, it's just an attempt to re-use old footage and otherwise take the week off from production! Awful.
UPDATE: By the way, it isn't just me who hated this episode. At the 50th anniversary Star Trek convention in Las Vegas, this was voted as one of the 10 worst of all episodes from every Trek franchise! That is some ignoble designation!