In The Deep Sea Diver's Syndrome, lucid dreamers called mediums dive into their dreams to retrieve ectoplasms - sticky blobs with curiously soothing properties that are the only form of art in the world. David Sarella is a medium whose dream identity is a professional thief. Only the dives require an extraordinary amount of physical effort, and as David ages, they become more difficult. David decides to go down one final time, in the deepest, most extravagant dive ever attempted...