In Star Trek Discovery Season 3, Episode 12, Osyraa stages a fake attack on the Discovery as it approaches Federation HQ so that Starfleet will let them in without use of comms. It works, and Admiral Vance (Oded Fehr) doesn't realize it until it's too late. As shields go down to let Discovery in, Book and Burnham crash their way into Discovery's shuttle bay. They devise a plan to have Burnham search for Stamets undetected.
Meanwhile, the Discovery's bridge crew and Ryn are being held captive in the ready room. Zareh returns after being left to survive in the ice back in episode 2. Book gets captured by Zareh and is placed with the bridge crew and Ryn, and together they must figure out a way to take back the ship and its operating system. Osyraa enlists Aurellio (Kenneth Mitchell), one of the greatest scientists in three sectors, to figure out how the Spore Drive works on Discovery.