Spoilers! But, mercifully, not very big ones. Before they hurriedly took it down, film fact site IMDB briefly posted a two-sentence synopsis for 'Fantastic Beasts and Where to Find Them 2', which isn't due until Christmas of 2018 (how can we possibly wait that long?). It's only a snippet of info, but of course Harry Potter fans have been picking over every word, trying to read between the lines and glean as much as possible about the new movie.
The IMDB synopsis read: 'Newt tries to move on, but Leta keeps turning up when he least expects it. After a while, he realises she is only there to tell him about Dumbledore, who needs to defeat Grindelwald.' We already know that the new movie will be set two years after the first, with Newt back in England having published his 'Fantastic Beasts' book. We also know that the Leta referred to is Leta Lestrange, his Hogwarts crush who broke his heart. She's presumably related to Bellatrix Lestrange, the mad witch played by Helena Bonham Carter in the Harry Potter movies, which we have to take as a pretty bad sign.
Potter fansite The Leaky Cauldron have posited that Dumbledore might be seeking Newt out for some advice on the nature of Obscurials, those adolescent wizards and witches whose inability to express their power causes them to create a dangerous Obscurus. Given that actor Ezra Miller - who played the young man who created and was seemingly killed by his Obscurus in the first movie - is once more listed in the cast, this does seem likely. A further theory implies that Dumbledore's sister Ariana, whom we know died at the age of 14, may have been an Obscurial herself.
All will, of course, be revealed in time. Until then, expect the Potterheads to pick over every nugget of info that drops into the public sphere - but don't expect every theory to come true.