A man stricken with nitrogen narcosis disappears into a shapeless eerie ocean mass. Primus swims to investigate. Bill Bolton, an ex-frogman(Dan Chandler) is dying in an underwater habitat. The only doctor who can perform a tracheotomy to save him, has never made a descent. Carter Primus (Robert Brown) and Charlie Kingman (Will Kuluva) guide the doctor (Mike Road) 320 feet undersea, but the doctor develops nitrogen narcosis and Primus must perform the tracheotomy himself.
Recaps1x2: Deepest of the Deep recap
: "Deepest of the Deep." Nicola (Susan Oliver), a girl friend of Primus steals an untested, underwater breathing device, which can bring a diver from the ocean floor to the surface in twenty minutes instead of the normal five hours. Unaware that the breathing unit has been mechanically altered, and is lethal if used, Nicola attempts the dangerous test dive... read more.