The "sentinels" developed by the surviving "bad" humans are winning the war against the mutants. Having derived tremendous knowledge about the mutants from Mystique's DNA after her capture, humans have perfected these soldiers who know exactly how to fight the mutant super powers.
There is only one way to avoid annihilation.
Send Logan (Hugh Jackman) fifty years into the past, and stop Mystique (Jennifer Lawrence) from assassinating Dr Trask and the resulting chain of events that led to the deployment of the sentinels, and the deadly human-mutant war.
Typical X-Men movie with some high class SFX, and thankfully, pretty effective 3D that's an enhancement to the experience...
Would love to see JL spend more time out of that silly Mystique costume, though!