Now 83, Banner can't imagine facing Alcatraz alone, at night. "I don't believe in spooks," he said, "but why on earth would a person want to do that?"
Amid a driving rain, a ranger hands Johnson the keys to the island — hurrying toward a ferry that soon whisks away the last of the day's 5,000 visitors.
Johnson stands solitary amid the gathering seagulls. The big birds are now everywhere, lined up on walls, circling like vultures.
They make him uneasy.
"It's like they're watching me, to see if I'm going to crack," he says, "like in that Alfred Hitchcock film, 'The Birds.' "
He makes a sweep for any tourist stragglers and settles in for the long night.
Johnson's father was a prison guard in upstate New York. He has the job in his blood. But Alcatraz is different.
The last rays of sun now gone, the island fortress becomes a grim, humorless place, the stuff of black-and-white 1950s crime photos. Johnson plays upbeat music on his iPod — Prince, Wham, Michael Jackson — to lighten the gloom.
He earns overtime pay for his 18-hour shifts (3 p.m. to 9 a.m.), but sometimes, in the dead of night, he says, "it seems like blood money."
At 8 p.m., dressed in a black cap and windbreaker, his radio squawking with park police chatter, Johnson winds his way up a switchback as birds dive-bomb from ledges. In the rain, the cell house looms up ahead like a haunted castle.
He walks cellblock rows that inmates nicknamed Broadway, Sunset Alley and Seedy Street. He enters a solitary cell, its heavy iron door creaking. The tiny quarters remain perfectly black even after his eyes grow accustomed to the space.
He stops at the cell of Frank Lee Morris, whose daring breakout was immortalized in the film "Escape from Alcatraz." Morris and two others left inside their cells dummy heads fashioned out of soap and toilet paper — complete with hair from the barbershop. The idea was to fool guards while they left through holes chiseled in their cell walls.
Johnson looks at a model of one fake head left in the cell as a tourist display. He knows how the men felt: "Ten years here? I'd go crazy before that."
By dawn, the night watchman is weary of the Rock. Passing the keys to a ranger, he makes his own escape from Alcatraz, the sun on his face.