In the penultimate book of Captain W.E. Johns' space adventures, the crew of the Tavona travel yet further and see yet more unbelievable sights!

First up is the planet Krona, whose seemingly youthful inhabitants can live for centuries. What is in their food that sustains them? Is this something that could help revolutionise medicine as we know it? Of course, something so valuable will always have its hunters - and not all of them are as virtuous as the Professor.

Tiger and his team will need to protect the natives of Krona, and persuade them that Earth is no threat in order to win the day!