Batman has assembled a Justice League of America which includes:
In the book each of the members are around the country fighting crimes or working on projects of their own when a call from Bats comes in about an Alien incursion that he wants to respond to. The leader of the Aliens is Lord Havoc and he basically wants to "save" humans from themselves by controlling them. Very typical bad guy move.
This issue was kinda lame in my opinion but I will give it one more issue to see where it goes. The only reason I picked it up was for Batman and the DC Rebirth #1's have been excellent so far but this one didn't live up.