Alannah Curtis is a singer-songwriter who is a newcomer on the Nashville music scene.
Introduced in the final season episode Where the Night Goes, she meets Will Lexington, Avery Barkley and Gunnar Scott after it is suggested by Bucky Dawes that they could use a female singer in their lineup. They invite Alannah to join the band and they prove to be a huge hit, although tension arises when the public start focusing on her as the main star of the group.
Gunnar finds himself attracted to her and they end up sleeping together after she tells him about her parents, saying she got her love of country music from her mother. However, he soon becomes jealous of her maintaining contact with an ex-boyfriend and tensions within the band are soon at an all time low. It also turns out that Brad Maitland wishes to poach her away from the group, which she objects to.
While the Last Highways perform on a television show, Will Lexington collapses during it and she looks on in shock as EMTs tend to him, only to find him unresponsive.
She starts to form a relationship with Avery Barkley which causes tension with fellow bandmate and fling Gunnar Scott and the latter breaks up with her but is unable to get over this especially when he discovers that she and Avery are dating. This causes tension within the band and she decides to leave and sign with Brad Maitland's label. She continues her relationship with Avery until Juliette, having escaped the cult, arrives home to find them together. Alannah tells Avery that she cannot be the cause of a family breaking up. They split up and Alannah presumably leaves town.