This week on "Supergirl," James (Mehcad Brooks) made his debut as Guardian, while Alex (Chyler Leigh) came out to Kara (Melissa Benoist). Meanwhile, it was revealed that Mon-El (Chris Wood) made a terrible career choice, but he was able to redeem himself before getting kidnapped in the last few minutes of the episode.

While out on a walk, Alex told Kara about having feelings for Maggie (Floriana Lima), adding that she thinks that she has known for quite some time that she's gay. She recalled spending time with her best friend when she was younger, and just when she started falling for her, they grew apart.

Later, Kara apologized to her sister for not creating an environment that encouraged Alex to talk to her about her feelings. Kara said that all their lives, Alex and the entire family were preoccupied with keeping her secret that there wasn't room for her at all. When Alex got turned down by Maggie, Kara was there to comfort her, and she held her sister while she cried.

James donned the mask and suit that Winn (Jeremy Jordan) made for him, and the two made a pact not to tell Kara about it for the meantime. Guardian showed up while Mon-El and Kara were battling an alien parasite, and she asked who he was.

"A friend," Guardian answered before speeding away on his motorcycle.

Mon-El took Kara to the alien bar where he got her drunk on alien rum. It was revealed that he has been working as a hitman for a bookie, which disappointed Kara. Later, he proved that he can do so much more by helping with the alien parasite threat, but shortly after, Mon-El got kidnapped by CADMUS.

Next week, in the episode titled "The Darkest Place," Supergirl heads out on a solo mission to rescue Mon-El. While fighting to free her friend, she comes face-to-face with Cyborg Superman.

Elsewhere in the episode, Guardian tries to clear his name after being accused of a murder committed by another vigilante. Meanwhile, the blood transfusion that saved Hank's (David Harewood) life in the last episode appears to have bad effects on him.

In the promo for the episode, Kara can be heard saying that Guardian is not a vigilante, but a murderer. Later, James learns that his alter ego has made headlines as Guardian is now being accused of a crime.

Mon-El is seen attempting to escape from CADMUS, and in a shocking scene, Hank kicks and punches Supergirl, who appears reluctant to fight him. When asked why he's doing this, Hank answers, "Because it's time for you to die."

"Supergirl" airs Mondays at 8 p.m. ET on The CW.