The Orpheus' team of scientists are on a mission to find a renewable source of energy in the depths of the Arctic Ocean. The last team who went died in mysterious circumstances, so the Orpheus crew are already feeling nervous when a salvage inspector unexpectedly joins their mission. What does he know about the lost crew, and who is he working for?

The Orpheus crew's quest for renewable energy has led them into danger. They're trapped on Volos, a Russian submarine, and its nuclear reactor is dangerously overheating. Whoever shuts it down will be exposed to lethal radiation. Who will draw the short straw? Meanwhile Clem is determined to find out what part the Volos had in his wife's death.