Wow, that Taylor Swift can keep a secret. She surprised her fans very late Thursday night with the perfect Christmas present: a new song, “Safe & Sound,” which will be on “The Hunger Games” soundtrack. Better yet, the lovely, acoustic song features The Civil Wars.

We don’t know much about how the whole thing came about, but Swift started dropping hints via Twitter earlier in the evening that she had a surprise, and then, wham. The song, written by Swift and Civil Wars,  is a lullaby of sorts, as she and The Civil Wars’ Joy Williams gently sing “Just close your eyes, the sun is going down/you’ll be alright, no one can hurt you now/Come morning light, you and I will be safe and sound” as a guitar and drum insistently and powerfully build, but never overwhelm the delicacy of the track. It's one of the prettiest songs we've heard Swift do.

[More after the jump...]

The song is already for sale on iTunes.  The movie, starting Jennifer Lawrence and Josh Hutcherson, opens March 23.

What do you think? When you think “Hunger Games,” do you think Taylor Swift?