BILLBOARD – A month ago, when holiday shoppers were scrolling through websites for gifts and rockin’ around the Christmas tree, it was easy to miss the quiet release of a three-song EP by the developing sister trio The Castellows.

But tucked onto the end of Alabama Stone, issued Dec. 6 by Warner Music Nashville (WMN), was an exquisitely melancholy song, “Girl That Boy,” that’s a bit of a mystery. Even though the listener doesn’t know it’s a mystery the first time through until the last few seconds.

At the end of its three-and-a-half-minute run, “Girl That Boy” employs a lyrical flip, unexpectedly changing its innocent meaning. It’s jarring, refreshing – and practically demands a second listen, if for no other reason than to figure out how the storyline ended up in such a surprising place. It’s such a fluid revision that the song’s conclusion can be seen in at least five or six nuanced ways, a scenario that’s entertaining to the group.