The Taelons introduce interdimensional travel to human customers. A young deaf-mute boy and his mother become separated during their travels through the portal. The boy appears and is now able to speak and hear. The boy is examined by Dr. Park, a resistance doctor, who discovers that he has been implanted with a device to restore his missing senses. Boone suspects that the Taelons are using the portal to perform experiments on humans. Doors sends Sahjit through the portal with a tracking device.

A holographic image of Rayna, who was consumed by an alien probe, tells Augur that the Taelons are dismantling the probe which will kill her, and they will learn about the Resistance's secrets. Hearing of Rayna's appearance, Sahjit is determined to bring her back. The Taelon lab is under intense security and Augur hires a special operative, Michael Sloane, to lead the resistance team to infiltrate the Taelon compound to destroy the alien probe.

Divers stumble across a strange radiant canister while searching for sunken treasure. Upon opening the canister an alien being known as Ha'gel is released from its prison and assumes the identity of one of the crew and destroys the others. Boone is called to the crime scene and his suspicions are raised when he finds Taelon writing on the empty canister. Upon questioning, the Taelons tell Boone that Ha'gel is the last of an alien criminal caste. Afraid that Earth will learn the truth, the Companion's recruit the help of Beckett to deal with Ha'gel. Ha'gel assumes Sandoval's form, and confronts Beckett.