I was in Blackreach with Lydia and she went missing when I went into one of the side instances. I went home and went to Dragonsreach went back home waited 4 days she never showed up. No courier showed up so I knew she wasn't dead. So I used the player.moveto command and there she was in a cell inside an instance I never seen or heard of in 1000 hours of Skyrim. All of the wikis on TES say its a prison for Winterhold.

I have no clue what she did to get there, how she got there and if she would have stayed forever. Lydia, has no dialogue options for the place. Is this some kind of rare bug or safeguard for lost followers?

What kind of crime do you think Lydia committed? I think she might have tried to carry someones elses burden without their permission.

Serves her right for watching me sleep in my house in Whiterun.