The Mast at Cairn Dubh

≈ 6 min

At Cairn Dubh relay station — a wind-battered iron hut perched on a 740-metre summit — technician Rona Gilbride has been found locked out on the hillside path, and inside the hut, the station's secondary transmitter (unit TX-2) has been found powered down and its frequency dial forcibly re-set to a rival relay's band. The Communications Authority suspects that station contractor Euan Stark used unsupervised access to sabotage TX-2 and steal the copper-core feeder cable routed through it, making rival band seizure appear accidental. You are asked to establish the exact sequence of events from Gilbride's arrival on the hill to the moment the sabotage was discovered.

The scene

Cairn Dubh hilltop radio relay station, a single-room corrugated-iron hut housing transmitter racks and a barometric log recorder, Scottish Highlands, present day

The events

Gilbride is locked out and the copper feeder cable is removed
Gilbride signs into the site log and enters the hut
Authority inspector Hamish Calder reaches the summit and documents the scene
The kerosene heater is lit inside the hut
Stark arrives and is admitted by Gilbride
Stark exits the hut via the rear service hatch

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This case first aired on July 27, 2026. A fresh forensic runs every morning — same rules, five minutes, one solution.

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