• Kim and Khloé Kardashian put their investigative skills to good use
  • North West's parody Instagram account has over 8,29,000 followers 
  • The new episode of 'Keeping Up With the Kardashians' drops every Thursday 

Kim Kardashian is taking her sister Khloé Kardashian's help to find out who is running a parody account for her eldest daughter, North West.

In the latest sneak peek of the "Keeping Up with the Kardashians" Thursday's episode, the sisters try to find out who is behind Nori's Black Book Instagram account.

Interestingly, the account clearly mentions in the description: "My mom's a superstar all from a home movie [parody...NOT THE REAL NORTH WEST]" and shares an email address. The page has more than 8,29,000 followers, and it keeps increasing on a daily basis.

In the clip, Kim and Khloé first call family friend and celebrity hairstylist Jen Atkin on FaceTime and ask her: "Are you Nori's Black Book?" Atkin laughs and then says: "Oh, my God! I f-----g wish I was Nori's Black Book. My captions aren't that good."

Khloé then confesses to Atkin that she and her cousin Cici Bussey used to think that the hairstylist is behind the fake account. However, before disconnecting the call, Atkin says: "You know who I think it is? … Steph."

Kim, 40, then immediately takes her former assistant Stephanie Shepherd on a four-way FaceTime and tells her that she has a "serious question" to ask.

Khloé, 36, requests Shepherd to "look Jen in the eyes" before giving any response. "Are you Nori's Black Book?" Kim asks, prompting Shepherd to reply, "Oh my God. I wish I was f------ Nori's Black Book."

Kim then wonders why everyone is providing the same answer. Shepherd tells Kim that she thinks it is "someone random" who might be running this parody account. "I don't think any of your guys' friends are that funny," Shepherd continues. "No offense."

Khloé agrees and notes that if anyone in their inner circle has such a sense of humor to write funny captions, she "would hang out with them all the f------ time."

"We've ruled a few people out of who it could be for Nori's Black Book," Kim says in a confessional. "We've called Jen Atkin, we've called Stephanie, Cici … we've tried everyone and they're all ruled out. So, I [am going to] call Tracy, who works with me, and she's, like, queen top dog investigator. Anytime we want to play a prank or do something, she always knows what to do and say."

After Tracy Romulus also denies that she is not that person, she suggests to Kim: "Why don't we try to contact them and say that we want to send them some KKW products or why don't we just get their address and say we wanna send them a PR box?"

Kim calls it is a great idea that might work. After the release of the upcoming episode's sneak peek, the parody account shared the same clip on Instagram and captioned: "Uh-oh! Mommy and Auntie KoKo are trying to figure out who is "Nori's Black Book". They asked everyone they know, even Mason. Do you guys have any guesses???"

The new episode of "Keeping Up With the Kardashians" drops every Thursday.

Kim Kardashian and North West In this photo provided by Forum Photos, Kim Kardashian West and North West enjoyed the Ariana Grande Dangerous Woman show on March 31, 2017, in Inglewood, California. Photo: Getty Images/Rich Fury