The title contains the bare bones of what I have seen about this. Note that there was a 38-minute fan-made film in 2009, with different cast, writers, and everything, of which I have seen a couple of minutes before I stopped watching. But I would guess this new film covers roughly the same ground, to wit: Gandalf’s and Aragorn’s efforts to find Gollum before (? I think) he got captured by Sauron and spilled those two critical words that started LotR rolling.
I saw this info a couple of days ago in a YouTube video from the channel Nerd of the Rings. At this stage, the movie is “in development” according to IMDB.
I have truly mixed feelings (rather like Candy at the end of her book) about this. On the one hand, these are the people behind the LotR movies. On the other hand, these are the people behind the Hobbit movies. I am trying hard to keep an open mind and see what develops. Since there is very little (that I’m aware of) actually written about these events, I guess they are entitled to make up events and characters, as long as they fit within the legendarium. They are going to have to invent a lot, it seems to me, to fill up a whole big-time movie.