Kara's going to find out something unexpected about her boyfriend Mon-El when the next episode of "Supergirl" season 2 airs in just over a week's time.  

A trailer for the episode, entitled, "Star-Crossed",  teases a visit from his home planet of Daxam by his parents, played by Teri Hatcher of "Lois and Clark" fame and "Hercules" star Kevin Sorbo.  

They will reveal that their son is not exactly who Kara thinks he is - he's a lot more extraordinary.  He is in fact the Prince of Daxam. 

But in the trailer, Kara can be seen admitting some reservations around the revelation and what this could mean for their relationship. 

Executive producer Andrew Kreisberg hinted in an interview with TV Guide that it could alter the dynamic of their relationship for the worse.

"I think what's interesting about it is, he doesn't quite get it's the cover up not the crime, which I think is really the issue," he teased.

In addition to this plot twist, there's something else for fans to look forward to as the episode also marks the start of the musical crossover between "Supergirl" season 2 and "The Flash" season 3.

Reports tease that Supergirl will be attacked by the Music Meister in the first part, while in part two in "The Flash", Mon-El and Hank Henshaw will turn to Barry to help her.

Kreisberg shared with Entertainment Weekly that the idea of a musical episode has been something of a long-running joke that is now becoming a reality.

"We've always talked about doing it, from the very beginning, more in a joking way," Kreisberg said.

Fans can tune in to the next episode of "Supergirl" season 2 on The CW on Monday, March 20, at 8 p.m. EST.  For the musical crossover with "The Flash" season 3, they can make sure they catch that on Tuesday, March 21, at 8 p.m.