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Thank you. It's early morning on February 12, 1994, outside the National Art Gallery in Oslo, Norway. Snow falls softly onto the face of 18-year-old William Osheim as he stops walking and stares up at the arched second-floor window of the grand brick building.

William silences the timer on his wristwatch. The moment he's been worrying about for weeks has arrived.

He signals to his accomplice to get the ladder from the roof of their car, which is parked on the street nearby.

Together, the two men placed the ladder against the window, and then William begins to climb. His hands tremble,

adrenaline surging through him. William's heart beats faster and faster. But in the falling snow,

the rungs of the ladder are becoming slippery. William is not eight feet above the ground when he slips.

The soft snow breaks his fall, and William is unhurt.

His accomplice scowls silently at him, though,

so William quickly gets to his feet and starts climbing again.

This time he reaches the top.

William checks his watch again.

Despite his fall, he's still on schedule.

And if all goes to plan, the next action will be perfectly timed with the arrival of the

cleaners at the back of the building. From his jacket pocket, William pulls out a small hammer

and breaks the window in front of him. No alarm sound.

Just as expected, the cleaners have switched off the security system.

Careful not to cut himself on the glass, William climbs through and into the gallery.

Inside, the room is dark, and at first, William finds it hard to make out what's around him.

...