Khloe & Kim Kardashian Try to Uncover the Truth About the Nori's Black Book Instagram on KUWTK

Kim Kardashian, P.I.?

In a hilarious sneak peek at Thursday's Keeping Up With the Kardashians, Kim and Khloe Kardashian try to solve the mystery of the infamous Nori's Black Book Instagram account. The parody page is written in the voice of North West and has garnered 774k followers since its creation in 2013. No wonder mom Kim wants to find out who's behind the anonymous fan account!

Khloe first speculates that hairstylist Jen Atkin is probably involved. "It's something she's so capable of," Khloe reasons. "It's so accurate, it just has to be someone in the circle."

The sisters FaceTime Jen, who denies any involvement. "I f––king wish I was Nori's Black Book!" Jen jokes. "My captions aren't that good."

Kim promises that they're "on the case" to find the mystery influencer. They call family friend Stephanie Shepherd next. "We have a serious question to ask you," Kim starts. "Are you Nori's Black Book?"

Kim Kardashian & North West's Cutest Pics

"Oh my gosh, I wish I was f––king Nori's Black Book!" Stephanie responds.

"Why is that everyone's answer?!" Kim jokes.

Yet Stephanie gives a bit of a hint: "I really think it's someone random because I don't think any of your guys' friends are that funny, no offense," she helps.

Khloe has to agree. "No one is that funny. I wish. I would hang out with that person all the f––king time!" she laughs.

But it looks like Kim and Khloe are giving up their amateur search and have to call in "queen top dog investigator" Tracy Romulus. The Chief Marketing Office of KKW Beauty advises that Kim reach out to Nori's Black Book directly to send KKW beauty press products. Then they'll have the true users' home address to further investigate.

"If this works, then we'll finally get out answer," Kim concludes.

So who really is Nori's Black Book? Check out the hilarious clip above for a sneak peek ahead of Thursday's all-new episode!