Rachel Bilson and Kaitlin Doubleday are heading to Music City.

Nashville has booked the O.C. and Empire alums to join the cast in mysterious roles when the show returns for the back half of Season 5 on CMT.

Bilson and Doubleday announced the news with separate Instagram posts Thursday night after Nashville's midseason finale aired on CMT. Details about their roles are scarce; however, some small clues can be found in the actresses' social media posts.

Nashville boss reveals how the show will move forward without Rayna

Bilson's photo indicates her character will have dealings in some capacity with Highway 65, Rayna Jaymes' (RIP) record label.

Music city, here I come🎧#nashvillecmt

A post shared by @rachelbilson on

And, could Doubleday's character be taking the stage at the Bluebird Cafe sometime in the near future?

This will definitely be a change of pace! #NashvilleCMT

A post shared by Kaitlin Doubleday (@kaitlindday) on

Fans will have to wait a while to find out, as Nashville is going on an extended hiatus and won't return with new episodes for a few months. (An exact premiere date has yet to be announced.) But the castings will leave viewers with something to speculate about in the meantime.

"We welcome Rachel and Kaitlin into our incredibly talented ensemble," showrunner Marshall Herskovitz said in a statement. "We fondly anticipate the second half of the season filled with surprising twists and turns that make Nashville so beloved by the fans."

In addition to her breakout role on The O.C., Bilson previously starred on Hart of Dixie. Doubleday's Empire character Rhonda was killed off earlier this season.

Nashville Season 5 is available on Hulu.