While reflecting on past battles, Siren comes up with a new plan to defeat the Pretty Cure. Siren captures Hummy in a buuble and impersonates her in front of Hibiki and Kanade. Kanade realizes Siren's identity right away because of her necklace, and her and Hibiki try to find a way to get Siren to lead them to the real Hummy. But Kanade and Hibiki disagree on ways to handle the situation. Siren ends up trapping them in different dimensions so they can't transform together, and releases a door negatone to spread sorrow over the city. Cure Muse shows up and uses her power to stall for time, saying she is still not an ally to the Pretty Cure, but if a new Pretty Cure were to appear, then she would reconsider joining them. Hibiki and Kanade's feelings reach each other and they are able to break free of the dimensions. They transform, and even though they are still fighting, are able to defeat the negatone. Hummy says that even though Siren keeps tricking her, she will always be Siren's friend, even though Siren thinks that friends can't be trusted.
ハミィがセイレーンのネックレスを付けていることに気づいた響。それを見て、きっとセイレーンがハミィに化けたのだと推理する。一体セイレーンが何をたくらんでいるのか、ハミィがどこにいるのかを響たちは探る。
