Recently on the Flash, right after Barry fails to talk Eliza out of injecting more of Velocity 9 which made her lightning turn blue before her lack of resisting the stuff made her kill herself off through disintigration, the lightning she gives off that turned blue made Barry realize that the reason Zoom was faster than him was because he injected himself with tons of the V9 which explains his violent and hostile behavior that the real reason the speed demon wants Barry's speed wasn't just to get faster but mostly to surpress the cellular degeneration after effects of the V9 just like Jay
Which made Barry realize that Zoom was infact the man that he killed and when Cisco confirmed the villain's identity while vibing his helmet Barry feels that he has again been betrayed, used and stood up by a speedster mentoring him that he ends up running to the cliffs in the forests and howlers over the falls in absolute anger that if he keeps up this rage and ignores listening to his friends trying to talk him out of it he is definately gonna kill Zoom
and because he was seen recently wearing a device around his emblem which must be what he using to travel through the multiverse indicates that this episode takes place after the next Flash episode where Barry confronts the Wraith and before his final confrontation with Zoom.
Now Flash's meet up with Supergirl in the Girl of Steel's 18th episode is sure to be a huge oppertunity for fans to see two heroes from two different shows running on 2 separate television networks team up together in person for the first time. Both of them are fast but at different altitudes, Flash is fast on the ground and Supergirl is fast in the air and the two are sure to be very good friends. While Jimmy is said to be a little jealous seeing him around Kara, Barry is sure to share his history with him, Winn and Kara
As for Siobhan, Kara's former rival at Catco lost not only her job but also her dream of being a journalist and Cat Grant's successor as Queen of all media and blames Kara for it and when Winn stopped her from getting Kara fired through email fraud he ends up pushing Siobhan over the edge which leads her to the awakening of her powers and now feeling betrayed by Winn feeling that he never was an honest friend to her at all, Siobhan is now lonely and hellbent with anger and starts going through a high pitch frequency rampage attacking Kara inside the high rise with her sonic scream before she becomes Silver Banshee and then somehow she discovers where the DEO was keeping Livewire and frees her.
And after the two rogue women meet up inside a condemed building where Leslie gives Siobhan the make over that completes her transformation into Silver Banshee and once Flash and Supergirl confront the two supervillains they will clash twice both in the hideout and in the park where they will be holding Cat Grant Hostage and with Siobhan's sonic screams so powerfully overwhelming how will Kara and Barry defeat her? Lifting her into space to shut her up just like Superman did to McDougal in Batman/Superman Public Enemies, freeze her with her frost breath, Flash confusing her with his speed mirage and then knocks her out, blow her away with wind crated by waving his arms superfast, or by throwing lightning at her? Surely they won't kill Silver Banshee and she won't get killed off after this episode because sure enough there will be more back story to explore on the character later in the Supergirl series most likely in season 2, especially on how she was able to start unleashing sonic screams without performing any magic rituals.
And finally Trajectory, because the EP of the Flash series chose to waste Trajectory by making her kill herself off like a lab rat with V9 overdoses that incinerates her leaving nothing but her costume, there is hope that Eliza Harmon's earth 2 doppleganger is alive and if she becomes Trajectoy of Earth 2 without using the V9 drug, then hopefully if Harrison Wells had laced the speed dampening serum he recently injected into Zoom with the same stuff that he used to steal Barry's speed, then draining the speedforce completely out of Zoom and letting the V9 drug's after effects in his system destroy him would be the thing Barry needs to do to defeat his greatest enemy and then once all the Speedforce inside of Zoom is drained he will give it to Eliza who will become the next Metahuman speedster after Jay to protect Central City in Earth 2. For now catch Batman VS Superman Dawn of Justice right now and be sure to catch the Supergirl/Flash Crossover at 8pm on CBS