'Billabong hosts a wedding in fine style. Wally drives Norah away for their honeymoon exploring, camping, fishing and hunting and going into little-known bush areas. Norah discovers Li Ning, a Chinese gentleman dying in a cave. He had been chased by three thieves trying to steal his bag of diamonds and a black opal that he wants to send to his son in China with his 12 year-old grandson, Li Chang.
'A map of the treasure’s location in the hills is with a trusted friend in Melbourne. Li Chang is hopefully there as well. Li Ning’s last wish is that Norah and Wally will find the gems and help Li Chang to return to his homeland before the thieves get in first. Jim is called to Melbourne to assist. They visit the Chinese friend, but the boy is not there. With the map in hand, they travel back by train. But the map is stolen from Wally’s locked bag when it is left unattended for a short break. Undaunted, they press on having already memorised a great deal of the map. Li Chang has been captured and tortured by two of the thieves. He escapes narrowly and runs into the Linton party, who protect him. Norah stays behind to nurse the child back to strength whilst the boys go off in search for the treasure. The map in their minds leads them to the exact spot, but too late. They chase the thief, who manages to hide the bag from them during the chase – observed by Li Chang, who retrieves it. At last Li Ning’s wishes are fulfilled.' (Publication summary)