An old friend resurfaces on the November 9 episode of House.

But will he remain a friend of House's after our favorite doctor discovers what this guy is up to and, most importantly, who he's up to it with?

Mysterious, poorly-worded questions aside, though, the installment is titled "Known Unknowns." As always, we'll recap it in full soon after it ends, posing the latest House quotes and a detailed review of what went down.

For now, check out the official Fox promo below, followed by a trio of images from "Known Unknowns."

[video url="http://www.tvfanatic.com/videos/promo-for-known-unknowns/" title="Promo for Known Unknowns"] [/video]

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.