Our conclave of detectives - together with Crypto insider Karen Moro - devise a plan to track any parts that might be stolen from the Crypto department. They hack into a network of air quality sensors across the city, enabling them to trace the radiation from isotope tags they've placed on suspect items. All goes to plan, until one of the items disappears off the screen - and when Anna goes to investigate, she disappears too.
Welcome to Perplex City.
Nothing can disappear entirely. Everything leaves a trace. There is always a trail to follow - if you can work out how to find it.
Kurt was convinced that there must be a way to track the equipment that has been vanishing from the Crypto department. However, he hadn't come up with a practical solution by the time he met up with Karen Moro again. It was Karen who thought up the only feasible plan.
Her idea was to hijack a network of airborne sensors currently used to monitor pollution in the city. The Air Quality System, or 'AQSYS', was composed of hundreds of tiny aerostats hovering in the sky, detecting all kinds of atmospheric changes - including the slightest increase in radiation. Karen realised that, if they tagged equipment with a radioactive isotope, they might be able to track the movements of anything stolen in future.
Anna spoke to Henrik at the Academy and asked him to relax a few security procedures, to allow them to use the isotope tags without setting off any alarms. Henrik, still rather smitten by Anna, agreed to her request.
Kurt hacked into the AQSYS system and, with the help of a few hundred Cube Hunters on Earth, prepared to put the plan into action.
A few likely pieces of equipment were selected for tagging. These were a Nelis Nuclear Isomer Battery, the Baker Spherical Magnetic Containment Field, plus new Reynolds Ionisers and Klebold Plates, to replace those that were recovered by the police.
Then, they waited.
Days passed. Violet, Kurt, Anna, Karen and Caine kept an eye on the AQSYS monitors, looking for suspicious activity.
Nothing significant occurred until Wednesday, when the parts were all picked up from the secure stores of the Crypto department. Taking separate routes, the parts all found their way to Grand Frederik's Station - except for the Magnetic Containment Field, which started moving off on its own. It sped away from the station - evidently in an attempt to shake off any pursuers.
But the AQSYS system worked well, and the equipment was successfully tracked south to the Old Town - where it disappeared. It was in Anna's neighbourhood, so she slipped away to investigate... and she, too, vanished.
So where is Anna? How did the equipment evade the AQSYS sensors, apparently without trace? And what can anyone do to find them?
There's only one way to find out. Play on.
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