For those unfamiliar with the X-Men comic books, the first couple of teasers for X-Men: Days of Future Past may have been overly cryptic. Apart from establishing that Wolverine had to go back in time to the 1970s and witness a lot of glass being broken, the teasers didn’t reveal anything about the plot. Why Wolverine had to go back in time was not even hinted at. For skeptics, it seemed like the only reason that time travel was integrated into the storyline was so that the film could feature the casts of both the original X-Men movies and X-Men: First Class, and thus make more money.

The new trailer, which runs two and a half minutes long, helps clarify things considerably. It turns out that a scientist named Bolivar Trask (Game of Thrones” Peter Dinklage) has invented a killer robot known as the Sentinel, which the government has mass produced in order to kill mutants. Professor X and Magneto are too busy fighting over Mystique to do much about it, and so the Sentinels nearly wipe out the entire mutant population. When Professor X and Magneto finally come to their senses, they send Wolverine back to the 1970s to stop Trask from inventing the killer bots.

The trailer also features a tantalizing glimpse of an old Professor X (Sir Patrick Stewart) talking to his younger self (James McAvoy) and a cool shot of Mystique (Jennifer Lawrence) jumping out of window with the Eiffel Tower in the background.

X-Men: Days of Future Past hits theatres May 23.