Finny stepped backwards until Bill nodded that she was far enough. Then he picked up the coils of rope.
His left hand held the bigger loops, and he took a second to make sure the loops all lay flat against his palm and weren't tangled. His right hand held the smaller coil and the grapple.
Bill stepped as close to the edge of the building as he dared and set his body into a relaxed posture while he took mental aim at the roof opposite and slightly below where he stood.
Finny heard him take a breath and then his right arm swung backwards and then forwards in a fluid arc. The grapple sailed towards its target with the little loops of rope uncurling behind it.
When the loops were gone, the bigger coils in Bill's left hand slipped one by one off his fingers with minimum friction and barely slowed the progress of the grapple.
Finny didn't realise that she had been holding her breath until the padded grapple bounced almost silently on the tarred felt of the roof of the Ranyhyn Building.
At the same time the grapple struck, Bill closed his fingers to prevent more rope than was necessary slipping into the void.
Slowly, he pulled on the line, dragging the grapple back to the edge where it caught on the parapet. Bill walked back to the tackle hanging on the pylon and tied the rope to the trailing end.
Then he started to pull on the hauling line of the first standing pulley and the rope between the buildings began to tauten.
Finny watched until she was sure the rope was about to snap, but Bill kept on shortening the tackle for several more pulls.
Then he tied off the hauling line and, making Finny grimace at the expected inevitable calamity, Bill swung off the tautened rope, letting it take his whole weight.
Nothing happened. Bill had been chosen because he knew what he was about when it came to rope work. When Bill let go of the line, it responded with a twang. He called Finny over.
"Listen good. When you get over, you take off the harness and hook it to the grapple. I'll loosen off, and when I give you the nod, you drop the grapple over the edge. Got it?"
Finny nodded. Bill led Finny over to the where the holdall sat by the edge of the building. From it, he took another rope. This one was already coiled and its ends tied so as not to trail.
He hung it over Finny's neck and shoulder.
"This is for the shaft." He wagged a warning finger in her face. "When you climb back up, don't leave it behind."
Finny nodded again.
"Ok, got it."
Then she gasped as Bill lifted her up and clipped the 'D' ring on her harness to the rope.
"Good. Don't look down, look at the rope."
Finny wrapped her legs around the line between the buildings and looked past her feet to the Ranyhyn Building's roof. She took hold of the taught rope in both hands and took a deep breath.
Bill let go of her and Finny began her angled descent, feet first to the building ten metres away.
Although her heart was pounding the whole way, the actual trip across the void was pretty easy. It didn't even make her arms ache, like climbing a drain pipe did.
Her feet touched the parapet and Finny swung her body through a hundred and eighty degrees so that she now had a close up of the crumbling stucco of the parapet.
Fortunately, the brickwork beneath seemed pretty solid.
Finny grabbed the parapet securely with one arm and eased her weight off the rope. Then she unclipped the 'D' ring and hauled herself over onto the flat roof.
Remembering her instructions, she unbuckled her harness and securely fastened it to a vacant tine of the grapple.
Job done, she squatted behind the parapet and watched the place she had just come from.
Bill was nowhere in sight, but before Finny could become concerned, she saw the rope between the buildings slacken and then Bill appeared.
He was walking slowly towards the edge while wrapping loop after loop of rope around his forearm like some old washerwoman with a clothesline.
When he got to the edge he stopped and gave Finny a single nod. Finny lifted the grapple off the parapet and dropped it over the side. She watched it crawl up the far wall as Bill reeled it in.
Then Bill gave her a short wave and disappeared back the way he had come. Finny was on her own.
Still squatting, Finny turned around. Remembering Joe's instructions, she picked out the air vent whose shaft would deliver her to the corridor outside Hanne Berg's office.
She almost set off towards it when Caution stepped forward and pulled on her ear.
What if the roof is booby-trapped? Finny lifted the goggles from under the thick collar of her suit and surveyed the roof around her. Image Intensify - nothing. Light Gathering - nothing.
Thermal Imaging - just the lazy meander of warm air escaping up the vents into the night. Finny slowly crossed the roof, her head turning left to right like a little radar dish.
She reached the vent safely. As per Joe's description, the large cowl covering the ventilator shaft was held on with several big wingnuts.
Loosening these, Finny was able to push the bulky aluminium cowl off the shaft and Finny was met by a warm draught of air from below.
She pulled a small flashlight from her wrist pouch and shone it down the shaft.
The grill which was her target was four, maybe five metres below her, well within reach of the length of rope coiled around her torso.
Clicking the flashlight off, Finny lifted the rope off her shoulder and tied one end around the solid-looking bracket that held the wing-nutted bolt.
She pulled on it as hard as she could to make sure it was secure and then dropped the rest of the rope down the shaft.
Excitement bubbled up inside her, eager to go, but Caution and Fear both held up a hand.
Excitement paced impatiently, but Finny stuck her head down the shaft and flicked through the night vision settings one more time, just to be sure.
Only then did she swing her legs over the lip of the shaft.
Climbing down the rope, Finny learned something new about her suit. The elbows, knees and butt of the suit had soft rubber pads embedded into the material.
This useful addition meant that it was easy to brace herself against the smooth metal of the ventilation trunking.
Before long she was face to face with the dozen aluminium slats of the grill she needed to get through.
One by one, Finny removed the slats and let them slide quietly down the wall onto the floor of the corridor. She surveyed the passage stretched out before her through the lenses of the goggles.
Five doors, and then the corridor turned left. Finny grinned. Five doors, but only one with three horizontal lines of laser light segmenting the doorway.
Invisible to normal eyes, but glowing bright orange to Finny's marvellous goggles.
Finny wiggled through the narrow hole, way too narrow for any adult, and fell into a squat on the floor. She adopted a 'ninja' pose and wondered if she looked half as cool as she was feeling.
She'd hafta get one of those cloth thingies ninjas wore round their forehead, a red one, yeah.
Sill in ninja mode Finny slid dramatically along the wall before performing a twisting jump to land before Hanne's office door in what she figured was a pretty real looking Kung-Few attack pose.
Excitement was having a field day while everyone else watched her manically jumping around their shared space. They exchanged glances with each other. Happiness shrugged, meh, let her have fun.