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. The more elaborate the dream, the better the ectoplasm. David Sarella is a medium whose dream identity is a professional thief. With his beautiful accomplice Nadia, he breaks into jewelry stores and museums, lifts precious diamonds, and when he wakes, the loot turns into ectoplasms to be sold and displayed. Only the dives require an extraordinary amount of physical effort, and as David ages, they become more difficult. His dream world--or is it the real world?--grows unstable. Any dive could be his last, forever tearing him away from Nadia and their high-octane, Bond-like adventures. David decides to go down one final time, in the deepest, most extravagant dive ever attempted. But midway through, he begins to lose control, and the figures in the massive painting he's trying to steal suddenly come to life and starts shooting"--