I'm basically watching The Flash. I don't watch all the Arrowverse shows.
I was watching The Flash S06E09 - "Crisis on Infinite Earths: Part Three". Then, I came to know that it's a five-episode crossover. So, I watched Arrow S08E08 and Legends of Tomorrow S05E01. In there, I got confused about the role of Pariah - Nash Wells. Later, in The Flash S06E10, I understood that Pariah is the one who actually released the Anti-Monitor. He opened the door for the Anti-Monitor by mistake. That's why everyone is holding him responsible, although he was just trying to find the secret of Novu - the Monitor.
Now, I'm a bit confused. Who held "the Anti-Monitor" captive in Earth-1 in the first place? Is it the Monitor? Which episode(s) do I have to watch to get a clear understanding of the Anti-Monitor's history?
And, another thing is - why didn't Novu/the Monitor (a good guy) tell everyone about the Anti-Monitor's location? He wanted to save the multiverse, I guess. Telling the heroes about Anti-Monitor's location should be the first step, to begin with. Then, the heroes could have stopped Wells to dig up that tunnel wall.