Star Trek: The Next Generation Season 3 Episode 22

Stardate: 43872.2. The crew are shattered by the apparent death of Data in a shuttle explosion, and are prevented from carrying out a detailed investigation when Starfleet gives them orders for a new mission elsewhere. However, the crew don’t realize that he was actually abducted and placed on display as part of a collection of rare and valuable items held by a disreputable character.