The story:
Rex, Tomm and the Phantom are attracted by a big gold flower in the big treasure room, but the Phantom ancestor responsible proves to be tight-lipped about its origins in the Chronicles, and the mystery deepens further when Hero and Devil return with a similar flower after a three day absence.

Retracing Devil's steps, a baffled trio discovers a golden boat moored in an underground lake. Sending Rex and Tomm home, the Phantom starts a hazardous journey on the lake and up (!) a waterfall, and on to the same remarkable discovery as his ancestor...