Credit: Video Still

The Pretty Little Liars Season 3 Halloween episode (Season 2, Episode 13: ”The First Secret”) is just a few weeks away (it airs on Tuesday, October 23), and this new sneak peek should make you more excited than ever.

In this clip from the episode, the Liars walk into a Halloween bash (it's on a train, 'cause why not) only to find American Idol star Adam Lambert performing "Cuckoo" — and yes, it's really Adam! Surprise!

Get a sneak peek of the performance below.

Don’t miss the next new episode of PLL, the Halloween special, on Tuesday, October 23 at 8 p.m. ET/PT on ABC Family.

Rebecca Martin is an editor at Wetpaint Entertainment. Follow her on Twitter @BeccaMartin47.

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