Sam and Dean Winchester move from tracking a murderous family pet -- all right, it was actually a skinwalker -- to investigating a UFO sighting in this week's episode of Supernatural, "Clap Your Hands If You Believe."

As you likely guessed from the title, the Winchester brothers don't discover aliens but rather fairies in their assorted forms. Here's the official episode synopsis:

While Sam (Jared Padalecki) and Dean (Jensen Ackles) are investigating a UFO sighting, Dean is abducted from a crop circle. However, when he awakens, he discovers he isn’t dealing with aliens, but fairies!

Unfortunately, only Dean can see the fairy that keeps attacking him which makes tracing and stopping them difficult. The brothers become even more perplexed when Sam’s investigation leads them to a world full of elves, gnomes and a leprechaun.

You can check out the preview clip, TV spot and photos below. Supernatural airs Friday at 9 p.m. EST/PST on The CW.

[gallery link="file"]