About a year ago, DC Rebirth occurred. The original Wally West made his way back into the DC Universe and warned of a coming threat that had been manipulating all the heroes since The New 52 began. Wally was fighting his way through the Speed Force and first went to Batman for help. When Wally disappeared, he left a familiar button behind–the button from the Comedian in Watchmen.
Batman is continuing his investigation of the mystery of the button and gets a nasty surprise. Check out the video below for some minor spoilers.
What the heck happens next? You really need to read Batman #21 to see the full details including some developments with Saturn Girl, last seen in DC Rebirth #1.
What the Heck is going on?!? 
That button is really getting around.