Major Characters:

• The Shadow/Lamont Cranston
• Pete Stockton: A contractor and an old school friend of Lamont.
• Pop Burkey: Pete's partner in the company Pete's father and Pop set up together.
• Joe Branley: A contractor and Pete's rival.

Featured Agents:

• Margo Lane
• Commissioner Weston

Minor Characters:

• Mr. Pine
• The Sandhogs

Synopsis: (Warning! Contains spoilers!)
100 feet under the river, working on the intercity tunnel, the listener is introduced to the "Sandhogs": specialized construction workers who work in areas under high atmospheric pressure. Mr. Pine, who is seemingly new, is called to the decompression chamber at the end of the day to join his fellow workers. He is informed about "the bends": a fatal condition in which the high pressure leads to the formation of nitrogen bubbles in the blood stream. To return to to surface without being properly decompressed would mean death. The decompression chamber helps them adjust to the deep tunnels or the surface atmosphere by either raising or lowering the pressure. But today would be different as the workers suddenly notice that the pressure in the decompression chamber is dropping faster than normal. It is too late to escape.

In the car, Margo notices that Lamont is preoccupied with his thoughts. He tells her about the death of the eight workers in the decompression chamber. An old school friend, Pete Stockton, is the contractor in charge of those men. The intercity tunnel is his first big project since the death of his father.

Upon visiting Pete, they learn that he filled with guilt over the men's deaths and plans to quit. A new contractor, Joe Branley will take his place on Monday. Pop Burkey, Pete's father's partner in the business, comes to tell Pete that the men still want to work for him (Pete) instead of Branley. Pete introduces him to Lamont and Margo. Burkey was a partner of his late father's when they broke into the sandhog business together. Burkey had suffered in an accident some time ago and couldn't work in the tunnels anymore, so Pete's dad found him work on the surface. When Pete leaves, Lamont asks Burkey for any opinions regarding the dead men. Burkey believes it was no accident, and reveals his theory that maybe Branley, who was competing alongside Pete for the tunnel project and was beaten out, is now out for revenge. Lamont considers it and decides to visit Branley as The Shadow.

The Shadow overhears Branley on the phone. Branley learns that the job has been handed over to him, and that he will be at the tunnel to "settle this thing once and for all". The Shadow makes himself known to Branley and demands to know who was on the phone, Branley confesses his innocence, but refuses to tell him who he was speaking to.

Lamont returns to the tunnel and is met up by Margo. Burkey has called Lamont, as he has noticed that someone has gone into the tunnel. He had found the elevator at the bottom of the shaft after returning from dinner. Burkey takes them down to the tunnel, and into the decompression chamber to adjust the pressure in their bodies to the pressure in the tunnel. As Lamont and Margo search the tunnel, Burkey decides to go back to the surface to prevent the intruder's escape. Margo wonders if this is a good idea. Just then, they hear a cry and the lights go out. Finding their way back to the door, they find it locked. Burkey doesn't answer their cries. Suddenly, the foreman's phone starts to ring. Answering it, Lamont hears Branley's voice telling him that he doesn't like his meddling and that he'll turn up the pressure until the tunnel explodes, causing the river to flood the area, killing both Lamont and Margo. He hangs up. Margo asks if it was Branley; Lamont thinks so. As the pressure builds, Lamont comes up with an idea to climb up the framework of the reinforced tunnel. They scramble up the structure. Suddenly, Margo slips and the listener hears the tunnel explode....

Commissioner Weston learns from Pete that even though the tunnel was drained, Lamont's and Margo's bodies were never found. They must have been washed away by the river. Burkey was found knocked unconscious outside the tunnel. Feeling that Lamont cared so much about him to risk his life, Pete will go back to the tunnel to finish the work in Lamont's honour. Weston assures him that cops will be stationed around to prevent mishaps, as he guesses that the decompression chamber accident was intentional.

When Pete goes into the tunnel. Weston is suddenly contacted by The Shadow, who tells him that he knows who the murderer is. The murderer will finish the job today by blowing up the pump, as his final victim is Pete himself. Hidden, Weston and The Shadow lie in wait. When the murderer appears, the police pounce on him. It is none other than Burkey himself.

Margo and Lamont visit a surprised Weston and explain their escape from death. They managed to reach the top of the structure before the tunnel exploded and found an air pocket. Lamont remembered that there was an escape chamber at the top of the tunnel, something Burkey had forgotten about. It seems Burkey hated Pete's father because he thought him responsible for the accident that ended his career in the tunnels. Also, Pete's father ended up marrying the woman he loves. So, instead of extracting revenge on the father, he decided to get back at the son and tried to implicate Branley.

In the end, Lamont and Margo got to do something they've been dying to do: read their own obituaries!