Episode 17 of The Trigan Empire
The Volcano Factory
aka The Terror of Mount Spyx
Het purperen licht (Dutch title)
The Purple Light (Dutch title, translated)
Written by Mike Butterworth
Illustrated by Ron Embleton
The Volcano Factory was originally published in 8 instalments in issues 383 (17 May 1969) to 390 (5 July 1969) of Look and Learn magazine.
It was reprinted in 1976 in 2 issues (24 January 1976 & 31 January 1976) of Vulcan comic.
It was reprinted in 8 instalments in issues 924 (6 October 1979) to 931 (24 November 1979) of Look and Learn magazine.
It is reprinted in Volume 2 of The Rise and Fall of the Trigan Empire (Rebellion).

Plot summary
Trigo goes with his wife Ursa to their summer palace in Bala. Bala is the most beautiful place on Elekton. It lies next to Mount Spyx. Janno and Keren are there as well. During the night, a volcanic eruption occurs and the entire city is destroyed.
From the crater, a strange rocket shoots upward. All the people flee to the nearby lake. The rocket lands by the lake, and a strange purple light shines from it. The crowd begins shouting that they will do whatever they are told, and they disappear into the rocket. The rocket flies back into the crater. Janno and Keren had been buried under the rubble of the palace together with Trigo. They were not at the lake. After freeing themselves, they also go to the lake. There they find a boy whose leg is trapped under a boulder. He tells them about the purple light. Janno, Keren, and Trigo are rescued by a hovercraft from Trigan.
Later, they return and descend into the volcano’s crater with rockets on their backs. During the descent, they also see the purple light. Trigo and Janno hide on a rocky ledge; the others disappear. As Janno and Trigo descend further, they enter an underground landscape. There they meet the Meekers — peaceful scholars in white clothing and with white beards. Long ago, they held power, but their slaves, the Zolls, rose up against them. Using the purple light — which the Meekers themselves had invented — the Zolls enslaved most of them.
They are attacked by the Zolls, and Trigo is captured by the purple light. The Meekers tell Janno about the machine that can trigger volcanic eruptions. When they are attacked again by the Zolls, Janno lets himself fall. He resists the purple light and does not lose his own will. After being held captive for some time, Janno escapes and manages to destroy the volcano-eruption machine. The Meekers free themselves and defeat the Zolls. Trigo and his wife return together with Janno and the others. Trigo renames the mountain Mount Janno.
Links
Plot summary (Dutch)
Downloads
MediaFire via British Comics Compilations