This article features spoilers from Season 6 episodes of "The Flash."
The premiere of season 6 showcased Barry going after Godspeed. He found out when he managed to get him, that this Godspeed was mute and emitted only a high frequency.
Godspeed makes a comeback, and Barry approaches Hartley Rathaway for assistance, according to the synopsis.
After Barry learns that after the crisis, The Flash and Pied Piper are foes, things go south though.
Meanwhile, Grant Gustin, who portrays Barry, spoke with Entertainment Weekly and confirmed 18 fans will see a change due to Crisis in "The Flash" Season 6 episode.
Hartley's episode was seen elsewhere in the "God Friended Me," and it was revealed that after the crisis, the Team Flash ally returned to his old ways. Episode 18 and the new dynamics between Hartley and Barry are likely to build more on this plot.
"When he comes back, Hartley really isn't a friend, but Barry will need to find a way to reconnect with Hartley and try to fix what 'crisis' has changed and stop Godspeed, and try to save the city," Gustin said in the interview.
Episode 18 of Season 6's "The Flash" will also show Iris trying to get off the Mirrorverse.
Official synopsis – “The Flash” Season 6 episode 18
"Godspeed and Pied Piper return-Barry (Grant Gustin) turns to Hartley Rathaway (Guest Star Andy Mientus) for assistance when Godspeed returns. But things get tensioned quickly after Barry realizes one of the Crisis changes is that THE FLASH and Pied Piper are now enemies. In the meantime, Iris (Candice Patton) is trying to evade the Mirrorverse. Amanda Tapping directed the episode written by Jess Carson. "Season 6 episode 18 of" The Flash "is scheduled to air on the CW Network on Tuesday (May 5). The title of the episode is "Pay The Piper."