When Robert Kanigher, Carmine Infantino and Gardner Fox introduced Barry Allen nearly 60 years ago, they probably never envisioned their new hero would one day appear on television. Singing songs from Grease. But listen, actor Grant Gustin is a Glee alum, so you have to utilize his golden pipes sometime. Barry’s vocal styling was only one of many noteworthy events in this week’s episode of The Flash.

Let’s start with the villain: Peek-a-Boo is the rogue of the week, but she’s more of patsy than master criminal, which doesn’t make her any less of a threat. Lashawn Baez commits her crimes in the name of love, using her teleportation powers to spring boyfriend Clay Parker from Iron Heights Prison. Clay Parker owes a local mob boss a great deal of cash, and Baez has to use her powers to help him score enough dough to remove the death mark. Why she doesn’t use her powers to take down the gangsters who are after Parker is never quite explained, making “Crazy For You” one of the more haphazardly plotted episodes of the show’s run.

Illogical plot points aside, Peek-a-Boo is still a cool villain with unique motivations, and the two battles she has with Barry are visually stunning and incredibly choreographed. Give the VFX guys a raise for this episode. Once again, Harrison and Team Flash find the way to defeat the villain -- Peek-a-Boo can’t teleport in the dark – and Barry executes the plan by smashing all the lights in a tunnel. It’s a cool fight sequence with an innovative visual pacing, but seriously, Barry really needs to figure out ways to take down the bad guys on his own.

After her defeat, Baez is imprisoned in STAR Labs, which continues to be a moral issue: She isn’t a stone-cold killer like Girder or the Mist. Does Wells and company have the right to hold her without a trial? This moral conundrum needs to be dealt with at some point.

Speaking of the STAR Labs prison, we got the next chapter in the villainous career of the Pied Piper. Last week, Hartley Rathaway told Cisco he knew the whereabouts of Ronnie Raymond, so Cisco frees the Piper and tracks down Martin Stein, providing the first mention that Stein and Raymond are now bonded as Firestorm. Next week seems to be the big Firestorm episode, but this week plants the seeds for the character’s one-of-a-kind origin.

Of course, Rathaway tries to escape multiple times, and Cisco proves he’s more than just a brain and a wit. He manages to kick Rathaway’s butt during the first escape attempt, declaring that he knows all about vibrations. Well, that just sets up a ton of possibilities, doesn’t it? Eventually, Rathaway does escape Cisco, forcing the scientist to go crawling back to STAR Labs and confess his mistake. They say confession is good for the soul, and while he’s at it, Cisco also reveals that he sealed Raymond into the reactor during the accident. One would expect Kaitlin Snow to be horrified by this revelation, but she forgives her friend, absolving Cisco of a tremendous amount of guilt.

Kaitlin’s generosity of spirit may stem from from the night she spent with Barry and the aforementioned karaoke. The two have a nice bonding session that provides a great deal of character exploration into Kaitlin. In fact, this week is all about love and loss: Barry is still dealing with Iris, Kaitlin is grappling with the loss of Ronnie, and even Peek-a-Boo has to face the betrayal and abandonment by Clay Parker, who leaves her to be captured by The Flash. Barry and Kaitlin have their bonding and singing session that sees the usually stoic scientist get really, really drunk. Barry takes her home and cares for her, creating some warm feelings in Kaitlin. When Cisco confesses his sins, Kaitlin forgives him because she wants to move on from Ronnie, who’s now lost in the being called Firestorm.

It seems Kaitlin perhaps wants to move on to Barry, as things got really CW. However, she doesn’t know that while she was trying not to puke in the restroom, Barry met a new love interest, Linda Park. Now, this might lead to some awkward moments if Wally West is ever introduced, but it seems Linda and Barry are now an item. To further complicate things, Linda works with Iris West, who’s having difficulties being taken seriously by other reporters. But Barry fixes that by giving Iris the scoop on the Peek-a-Boo case. Now that Kaitlin appears to carry a torch for Barry, could his involvement with another woman set Kaitlin on a darker, and very cold, path?

Lastly, we have some developments with Henry Allen, who becomes involved in the Peek-a-Boo case after Baez springs her beau from prison. Finally, Harry becomes a full character rather than a plot point, as he’s determined to help his son and Joe West solve the prison break. While snooping, Harry is stabbed, leading to the beautiful bedside revelation that Harry knows his son is The Flash. Think of Aunt May’s speech about heroism to Peter in Spider-Man 2 to understand the levels of emotion reached as Harry told Barry just how proud he was.

We would have been left with that moving and sweet moment, a warm feeling to take us into next week, if it weren’t for this week’s sweeper, in which two sewer workers are torn apart by a feral beast beneath Central City. A beast named Grodd.

Yeah, that’s what I’ve been waiting for!