This is the third book in a trio of books that carry a related storyline, picking up after the end of “Little Flower of the Sun”.

Summary.  This book consists of two stories, spliced together.  However, an incident right at the beginning of the book, namely a dancing light seen over on the Pelham side of the river, does relate to the second story.  The book then immediately veers off into the unrelated first story.  The Greek boy Stapoulos has a gang in Watertown, busy stealing and causing other mischief.  Bullen and Riffle Hare also appear on the riverbank, seeking the location of an old sundial on the edge of Burney’s Field.  They lure members away from Stapoulos’ gang, and Stapoulos is caught by the police.  Another boy, Bob Longlegs, appears and is also seeking the sundial.  Hawkins and Shadow Loomis find the sundial first, and buried under it a box of gold bonds that had been stolen from Judge Granbery.  The bonds are returned to the judge.  When the other boys learn about this, Longlegs is disappointed (as he had been seeking the bonds), but mysteriously, Bullen is relieved.  He turns out to be the grandson of a river pirate who had hidden gold loot in the area, and Bullen thought the sundial hid that gold.  The river pirate gold was instead hidden in a cave in the Pelham Ridge, and Hawkins, Judge Granbery, and Doc Waters find that gold.  After that development, Longlegs, Bullen, and the other boys leave the area. 

The book then resumes the investigation of the dancing light.  The light is from the hidden entrance to another new cave, in the Pelham Hills, the headquarters of the Fong Shu gang.  They have returned from China and are seeking the Emperor’s Sword (which never reached China and has been brought back to the area) and an antiquity called the Lacquer Fan; it is believed that whoever holds the sword in one hand and the fan in the other will rule the world.  Another Chinese gang, led by Kai Foo, also appears, seeking the same items.  The Kai Foo gang is arrested, and Fong Shu flees to China.

There are three distinct phases to this book, with the first story having two phases.  These are differentiated by who the main characters are, as follows:

Chapters 1 –12, pages 3 – 96 Stapoulos and his gang, ending with the arrest of Stapoulos

Chapters 13 – 17, pages 97 – 134   Bob Longlegs, Bullen, and Riffle Hare, and the race to find the sundial and the box hidden there, ending with these boys departing the area