The Flash came back with a bang in “Marathon,” which elevated an otherwise lackluster season to a whole new plane of existence. Perhaps preparing for Crisis on Infinite Earths, and its inevitable conclusion that nothing could happen to Barry, tied the new showrunner’s hands for the first half. Or perhaps he was just warming up before settling into a speedier storytelling pace. Either way, the midseason premiere foretells tighter storytelling and more interesting character-driven plotlines.

Iris (Candice Patton) led the storyline pack – also for the first time this season, which is no coincidence when it comes to the increase in quality. Since The Flash apparently opted for few timeline changes outside the addition of the return of early-season villains (which will soon be a blessing, I’m sure), Iris is still busy tracking down the source behind Black Hole.

The difference is that this time Iris actually gets to do more than delegate to Team Citizen; she’s on the front lines interrogating the CEO of McCulloch Tech, meeting with sources, and investigating leads the second she gets them. Kamila, Allegra, and Cecile (Danielle Nicolet) provide much-needed backup and act as soundboards, which is a wonderful reversal from the way the Citizen plot was developing in the first half of the season. And as a bonus, Joe (Jesse L. Martin) actually remembered he had a daughter and gave her the best pep talk in years.

Any eagle-eyed DC fan who knows that Evan McCulloch is the New Earth continuity Mirror Master probably wised up to the face that the CEO’s wife turned out to be named “Eva.” But despite knowing what direction the story might take, “Marathon” was full of believable twists and turns that showed off Iris’ journalism skills and built up more tension in one episode than Bloodwork managed to do over the course of 7. And the cliffhanger of Iris being pulled into the mirror? Let’s just say I can’t wait for Patton to wow audiences with her take on the Mirror World next week.

The B-plot of “Marathon,” in which Barry (Grant Gustin) clings to Diggle’s (David Ramsey) visit and a mask gift from Oliver for a semblance of closure, was perhaps less satisfying. Between already exhausting the Crisis goodwill and not having much screen time to develop Barry’s feelings on the matter, The Flash didn’t really make the search for mirakuru click. But it did help solidify Barry and Diggle’s friendship, opening the door for future guest star visits now that the progenitor show has exited the Arrowverse.

Back at STAR Labs, Cisco (Carlos Valdes) once more carried the weight of the multiverse on his shoulders and Valdes gave a performance to match. His guilt over removing his powers is perfectly understandable in a timeline where Harry and Jesse no longer exist, and it’s a relief to see that someone is trying to trace Earth-Prime changes in the new reality.

Not only did he get to operate as well-oiled machine with Team Citizen, and especially his girlfriend Kamila, Cisco also got a chance to deepen his friendship with Frost and Caitlin (Danielle Panabaker) alike. She takes the opportunity to offer him advice and a shoulder to lean on, and while the result is Cisco taking off for a soul-searching mission to piece back the timeline, at least fans can rest easy that he won’t be leaving the show.

“Marathon” managed to tie each of its storylines into a unified theme: it’s a brave new world, and all of The Flash characters need to adjust to it. The repercussions of a post-Crisis world may not be immediately clear, but a Mirror Master who does more that make things spin a little suggests they’ll be a whole lot more interesting.