Through The Looking Glass - S1.E19

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.