A World Aflame. Cap Kennedy Book 13

PILLAR OF FIREMillions of Years before humanity and other intelligent races learned to roam the Milky Way, the Zheltyana had created an empire among the stars - rose, triumphed, and vanished. All that remained were a few ruins, some artifacts, and the knowledge that their powerful scientific secrets awaited rediscovery. One such secret had been found on the feudal planet Naxos, under the tyranny of the half-mad Idalia Ancanette.
Her scientists had tapped its mystery to create a pillar of energy which promised to make Idalia mistress of a hundred worlds - if it did not destroy Naxos before it could be harnessed. Such an event called for the attention of Earth's master agent, Cap Kennedy, and his scientific crew. Because that column of atomic fire was a beacon that could herald a millennium or end in A WORLD AFLAME.