E.C. Tubb 
Jack of Swords 
The Dumarest Saga Book 14

Earl Dumarest continues his desperate search for his birthplace, and seems to be coming close to the mythical planet Earth.But his attention is temporarily diverted, as he is unexpectedly involved in a hunt for a nebulous ghost world in another galaxy.It is rumoured that in this fabulous land lies the mysterious Castle of Heart’s Desire, where every wish is fulfilled. If Dumarest can find it, then maybe — just maybe — he will be able to return to the planet of his birth.(First published 1976)