Supergirl season 4 episode 18 live stream: Watch online

Desperation mounts on Supergirl as the search for Lex Luthor continues. Read below for all the information you need on this week’s episode.

Is it just us or has Supergirl had as many hiatuses as episodes this year? Before tonight, the most recent episode aired three weeks ago, on March 31, and only one episode aired in all of February.

Maybe the constant breaks are why the show has been struggling to find its momentum lately. To be sure, it is still enjoyable, with surprising twists and memorable episodes like “Blood Memory” and “The House of L.”

But as the conflict between aliens and humans escalates and Lex Luthor becomes more prominent, Supergirl risks losing sight of the real-world stakes and thorny politics that made its first half of season 4 so gripping in favor of a more generic and bombastic story.

Put another way: we need more “Man of Steel” and less Man of Steel.

Hopefully, this week’s installment will put that anxiety to rest. Below is the official synopsis for the episode, titled “Crime and Punishment,” courtesy of The CW:

"WILLIE GARSON GUEST STARS — Supergirl (Melissa Benoist) and Lena (Katie McGrath) head to Stryker’s Island to search for clues on how to defeat Lex. At the prison, Supergirl tries to befriend a nosy prisoner, Steve (guest star Willie Garson), who may have insight into what Lex was doing, but he and all of the prisoners regard her as a traitor to the country and refuse to talk to her. Lena realizes Lex left behind clues for her and deciphering them could be the key to his whereabouts. Meanwhile, Kelly (guest star Azie Tesfai) encourages James (Mehcad Brooks) to talk to someone about his PTSD, and Alex (Chyler Leigh) faces off against Ben Lockwood (Sam Witwer) after he storms the DEO and acquires some powerful weapons to hunt Supergirl."

With the season finale still five episodes away, the chances of Lex being caught anytime soon are slim. So, at least in terms of the main plot, we’re expecting this to be a bit of a filler episode.

Of course, that doesn’t mean it has to be disposable. The synopsis suggests plenty of opportunity for meaningful character development, whether it’s Supergirl and Lena figuring out how to work together again or James confronting his feelings. James’s plot sounds the most intriguing; surely, Lex’s return will push him to open up more about his past, including his work with Superman.

Antonio Negret directs from a story by Rob Wright and teleplay by Lindsay Sturman and Aadrita Mukerji.

"Date: Sunday, April 21Start time: 8 p.m. ESTEpisode: “Crime and Punishment”TV Channel: The CWLive Stream: Watch live on Fubo TV. Sign up now for a free seven-day trial. You can also watch on The CW website or app."

Supergirl airs as part of The CW’s Sunday night line-up.