E.C. Tubb 
Melome 
The Dumarest Saga Book 28

"Welcome to the circus of Chen Wei! A spectacle of marvels culled from a thousand worlds! Things that will fill you with rapture!"There could be little to surprise Dumarest. But Chen Wei’s circus was special. It held Melome — the girl-child whose song could bring back forgotten data from the logs of lost spaceships and true visions of mythical Terra. She was surely the key to Dumarest’s next step — but that circus was more than an entertainment. It was a deadly trap . . .(First published 1983)