There may not have been a show that took as many wild twists and turns on The CW as Gossip Girl did. It also was a series that helped launch the careers of Penn Badgley and Blake Lively.

Here’s how it works. Gossip Girl ended in 2012 after six seasons with the revelation that “Lonely Boy” Dan Humphrey had been the blogger with the big mouth all along. (What a plot twist!) ...