Ep 4. In His Majesty's Secret Service

In "LEGO: Nexo Knights" season 4 episode 4, titled "In His Majesty's Secret Service," the heroes find themselves on a mission to stop the villainous Jestro from obtaining a powerful artifact. King Halbert sends the Nexo Knights on a secret mission to retrieve the Book of Forbidden Powers from the Vault of Ice.

The Knights must journey to the Frozen Wasteland and face off against Jestro's forces to reach the Vault. Along the way, they meet a young woman named Emily Jones, who has been sent on a similar mission by her own kingdom. Together, they team up to take down the evil Jestro.

As the group makes their way through the treacherous landscape, they encounter a number of obstacles and challenges. They must battle fierce creatures like Ice Berserkers and Shadow Slinkers, and use their Nexo powers to overcome obstacles like frozen bridges and icy caverns.

Eventually, they reach the Vault of Ice and come face-to-face with Jestro and his army. A thrilling battle ensues, as the Nexo Knights and Emily Jones fight to keep the Book of Forbidden Powers out of Jestro's hands.

Despite the odds against them, the Nexo Knights prove that bravery, determination, and teamwork can overcome even the toughest challenges. They emerge victorious, having saved the day and prevented Jestro from wreaking havoc on the kingdom.

Overall, "In His Majesty's Secret Service" is an exciting episode filled with action, adventure, and epic battles. Fans of the show will not want to miss this thrilling installment in the Nexo Knights saga.