[Originally aired November 5, 2017 on CBS All Access]

The Klingons are attacking the U.S.S. Gagarin when the Discovery arrives to lend assistance. They are unable to fire on cloaked Klingon ships and all of them have the cloaking tech. The Gagarin is destroyed in the battle and the Discovery uses the spore drive to escape. When Lorca contacts Admiral Terral, he is told that Starfleet's intel is that Kol has equipped the ships of all houses willing to swear loyalty to him with cloaking tech and that the Pahvo mission is of the highest priority if they are to defeat the Klingons. Lorca confirms that the away team landed on Pahvo eighteen hours ago.

As the ship comes out of code black, Stamets seems disoriented and addresses Tilly as "Captain" but is angry and rude when she asks him about it. She approaches him later and he eventually explains that he is experiencing something strange when he is navigating the spore drive. They agree to monitor the episodes without informing Dr. Culber.

On the planet Pahvo, Burnham, Tyler, and Saru are trying to reach a naturally-occurring transmitter which they mean to modify to use to detect cloaked vessels. They are approached by energy entities which lead them elsewhere. Saru tries to communicate with them but the vibration noise of the planet tires him and when he asks the entities to make it stop, they merge with him. The experience leaves him much more relaxed and in the morning, he informs Tyler and Burnham that they have been invited to stay on the planet indefinitely. 

On Kol's vessel, L'Rell approaches him to offer her loyalty but he says it isn't enough. She offers her services as an interrogator and goes to Admiral Cornwell's cell. After having her scream so that the guard leaves, she tells the Admiral that she wants to defect. When they are heading for her vessel, they are detected and Cornwell starts a fight which L'Rell kills her in.

On Pahvo, Tyler and Burnham clash on how to deal with Saru's obviously compromised condition. Tyler pulls rank and orders Burnham to follow the mission mandate and make the modifications to the transmitter. When Saru comes back, Tyler tells him Burnham and him had had a fight and she was walking it off. When Tyler asks why Saru is no longer bothered by the sound. Saru describes his new situation as being in harmony and Tyler confesses that he wants to not only defeat the Klingons, he wants to hurt them for torturing him.

Saru shares a Pahvon stone of harmony with him to help with his alleged angst but when they connect using it, he realizes that Tyler is playing the role of a distraction to allow Burnham time to reach the transmitter. He runs to the transmitter where she is about to contact the Discovery. He attacks her and tries to destroy the equipment. Their fight is interrupted by the entities transporting Tyler to their location. The Pahvons repair the transmitter equipment and the crystalline structure changes before their eyes.

On Kol's ship, L'Rell takes Cornwell's body to a disposal room and discovers many of her friends have been killed by Kol and left there as well. She vows revenge. She reports to Kol that Cornwell had revealed that the Discovery had new technology that could win the war. She swears her allegiance to him, accepting the face paint of House Kor but Kol announces that she is a liar and will be punished as such. He is interrupted when a crewman announces a signal is being received from Pahvo and it is an invitation.

On the Discovery, Lorca wonders if the mission was actually a success because the transmitter is only sending two signals, inviting the Klingons to their location. As Kol's ship is detected on long-range sensors, Burnham tells Lorca that the Discovery must protect the Pahvons.