Star Trek: The Next Generation: The Q Continuum

The unpredictable cosmic entity known only as Q has plagued Captain Jean-Luc Picard and the crew of the Starship Enterprise™ since their very first voyage together. But little was known of Q's mysterious past or of the unearthly realm from which he hails.
Until now.

A brilliant scientist may have found a way to breach the energy barrier surrounding the Milky Way galaxy, and the Enterprise is going to put it to the test. The last thing Captain Picard needs is a surprise visit from Q, but the omnipotent trickster has more in mind than his usual pranks. Kidnapping Picard, he takes the captain back through time to the moment the Q Continuum faced its greatest threat.

Now Picard must learn Q's secrets -- or all of reality may perish!