Simon Pegg offered a little bit of plot information from Star Trek: Beyond.
Obviously, those avoiding any spoilers should skip to the next article.
According to Pegg, the crew of the Enterprise is two years into their five year mission. They have “come to rest at a Federation outpost,” said Pegg; “a sort of diplomatic hub.”
But their relaxation is interrupted by the angry alien Krall (Idris Elba), who attacks the Enterprise and its crew.
“What’s the point of it [The Federation] all?” is the question that the film will try to answer, said Pegg. “We’re gathering a great community within the galaxy, but to what end? What does it all mean?”
In the short term, it means Kirk and crew are in for a rough time.
Source: Empire Online