WARNING: This article may contain spoilers for The Flash season 6 episode 18. Read at your own risk.

The Flash season 6 episode 18 is scheduled to arrive next week on The CW, with the title "Pay the Piper." This will be an interesting episode as it marks the appearances of some familiar faces. But for Barry Allen, their arrival will not that easy for him.

The Flash season 6 episode 18 sees the return of Godspeed, a murderous villain that could cause further chaos. Yet, his arrival may just be for this episode, given that the series is already dealing with Eva McCulloch, as well as the threat of the Reverse-Flash.

Meanwhile, the title already suggests that Pied Piper is coming back as well. He is a recurring character from the first season, so it's nice to have him back this time. However, he'll be completely different within this episode and may not help Barry in defeating Godspeed.

In this episode, Godspeed comes back to Central City. To defeat this villainous speedster, Barry turns to his old friend, Hartley Rathaway. However, Barry soon discovered that his friend has been reverted to his antagonistic ways because of the Crisis. Now, The Flash and Pied Piper are enemies.

As for what else is coming in The Flash season 6 episode 18, Iris will try to escape the Mirrorverse. Barry also needs to find ways how to get his wife back, given that she's been stuck in the mirror for a long time. He has to fight the Mirror Iris, while also trying to discover the truth about Eva.

Eva is the one who's pulling the mirror strings and has her own agenda. She also needs to settle her issues with husband, Joseph Carver. Hopefully, Barry may find a way to get this mirror mess sorted out. But then, his failing powers are still a concern and things get tougher for him.

Barry has been dealing with a lot of problems as of late and showrunner Eric Wallace teased that the truth about the Mirrorverse will have "tragic consequences" for him. Speaking to TVLine, Wallace also said Barry and Iris will experience the "rockiest month of their marriage."

Meanwhile, this episode serves the penultimate one before the season finale. Because of the COVID-19 outbreak, the current season had to be cut short. Hence, the series may or may not leave a huge cliffhanger. The remaining episodes that weren't filmed may also be featured in season 7.

The Flash season 6 episode 18 airs on Tuesday night, May 5, on The CW. The episode is directed by Amanda Tapping and written by Jess Carson.