'The Blacklist' season 4 episode 12 spoilers: Red gets rid of a spy in his organization; 'The Office' actress lands guest starring role

Tom (Ryan Eggold) goes undercover for Red (James Spader) on the upcoming episode of NBC's "The Blacklist" season 4.

Titled "Natalie Luca," next week's episode will see the Task Force track down an assassin. According to the official synopsis, the team must search for an elusive killer who does her job by imparting a deadly disease on her victims. Red is still worried about the breach in his organization, so he sends Tom on an undercover operation to look into the spy in his group. After Red discovered that there's a spy working amongst them, Tom must get rid of him without the others knowing about it. Red decided to trust Liz's (Megan Boone) husband to take the job because he has had many undercover missions over the years, and he has the perfect skills to execute Red's plan.

Meanwhile, a new female character will soon be introduced in the show. "Transparent" star Melora Hardin has been tapped to guest star in the crime drama as Isabella Stone. Described as a socialite by day and character assassin by night, Isabella is a Blacklister who is relentless when taking down targets. She is known for using methods such as public humiliation, scandal, and extortion.

Hardin played Tammy Cashman in Amazon's acclaimed family drama "Transparent" for two seasons. Despite her numerous TV credits, the actress is probably best known for her role in "The Office" as Michael Scott's (Steve Carrell) on-and-off love interest, Jan Levinson. Her film credits include "The Hot Chick" and "27 Dresses."

Hardin's Isabella will be introduced on the show's Feb. 9 episode, which airs two weeks before the drama's upcoming spinoff "The Blacklist: Redemption" premieres on Feb 23. The storyline will see Tom reunite with his mother (Famke Janssen) as they work with black ops professionals.

The fourth season of "The Blacklist" airs every Thursday night at 10 p.m. ET on NBC.