Though the Previously segment does not remind us of his existence, “Wake Up” heralds the return of Supergirl‘s long-lost beau, Mon-El (Chris Wood), and the discovery of his ship, which leads to a series of misunderstandings that last nearly the entire hour. In their separate corners of plot, Sam (Odette Annable) learns the truth about her origins while J’onn (David Harewood) learns something new about himself thanks to his father.

Welcome back to the team.

The most enjoyable storyline in “Wake Up” makes great use of Winn’s (Jeremy Jordan) comedic timing for perhaps the first time all season. His interactions with M’yrnn (guest star Carl Lumbly) are delightful, and his suggestion that J’onn take his father out on the town so he feels like less of a prisoner is very insightful. The irony is that M’yrnn doesn’t see himself as a prisoner – he sees his son as one. Despite enjoying the “brown water” (his name for coffee, as he can’t pronounce the word), he’s more concerned with how many times J’onn checks his “smart device” while away from the office. The accusation that J’onn is too immersed in work resonates strongly, given that his character has nothing to do outside the DEO and instead merely disappears when the rest of the cast leaves the headquarters. Hopefully the writers called this out in order to change it, and aren’t just lampshading for the sake of it. Regardless, J’onn responds by getting an apartment for himself and his father in a very sweet scene that promises a new start and a new home for them both.

Speaking of characters being trapped in the DEO, Mon-El is desperate to leave after being rescued by Kara (Melissa Benoist) and her team. It’s hard for them to understand why, given that he refuses to give an explanation. For a large part of “Wake Up,” we are only told that there are peaceful people in the pods and that Mon-El is worried for their safety. He seems on the verge of revealing some great truth to Kara many times, but either they are interrupted, she cuts him off, or he simply loses his nerve. As poignant as their reunion could have been, it’s undercut by this narrative stalling that is obviously designed to provide a shocking final moment.

After a failed attempt at stealing weapons and attacking guards, Kara confronts her ex in a very vulnerable and heart wrenching scene. She opens up about her nightmares of him dying and how hard life has been without him, but Mon-El remains unreceptive and reticent. This is frustrating to watch not only as a fan of Kara, but also as a fan of well-paced plots. One of the highlights of this story was James (Mehcad Brooks) getting another opportunity to be a good friend to Kara, though unfortunately that meant he had to remind the audience that season one never happened by telling her how the happiest he had ever seen her was when she was with Mon-El.

No life without wife.

Mon-El makes it back to his ship with Winn’s help, although Kara is not far behind. Together they prevent the pods from drowning the passengers inside them, and the Daxamite explains that a wormhole sent him to the 31st century where he lived for seven years. That explains how distant he feels from Kara, and the two of them have a touching scene in which he promises that he never forgot her (he has the necklace she gave him to prove it!). But a final interruption means that Kara has to learn about his wife Imra (guest star Amy Jackson) by watching Mon-El kiss her. I’m not sure why he couldn’t manage to say “I’m married” all episode, but Benoist sold that heartbreaking reveal like nobody’s business.

The most important plot line belonged to Sam, for whom “Wake Up” takes on another meaning. Her quest to understand the meaning behind her powers drives her to visit her adoptive mom Patricia (guest star Betty Buckley), who doesn’t even know her own granddaughter’s name. The tension between the two women is perfectly played by the actresses, though it’s a little jarring to hear of yet another parent on Supergirl who abandoned their child when their sexuality took an unexpected turn. In Sam’s case, it was getting pregnant with Ruby that broke her bond with her mother.

In a surprising turn of events, Patricia freely drops the bombshell that she found Sam in an alien pod, which totally revolutionizes Sam’s perspective on her powers. What once made her afraid now excites her, so she follows the obelisk she grabbed off the pod on a road to nowhere. Sam eventually reaches an area in the desert where the ground cracks open and a fortress springs up. The vision from her nightmares awaits her inside, ready to jumpstart her destiny as Reign. Once again, Sam is happy to embrace it until she hears that she’s meant to be a “world killer” – because that certainly doesn’t sound heroic. Matters go from bad to worse when the mysterious woman claims Ruby was an error who will soon be forgotten, which Sam immediately protests. If there’s one thing she knows, it’s that she’s a great mother who loves her daughter. But everything she knows falls away in one agonizing scream, and soon it is clear that Reign has awoken in her place.

What’s not clear is who or what Reign is. Sam was apparently designed rather than born, so is Reign a piece of her programming that’s taken over? Or is this a matter of possession, with another entity controlling Sam? We should find out after the crossover, but the shift was rather abrupt after such a slow burn. That confusion, as well as the lack of inter-connectivity among the three separate stories, made “Wake Up” one of Supergirl‘s weaker episodes in an otherwise strong season.

Supergirl airs Mondays at 8/7c on the CW.