Summer Reading for Middle School: Joshua Mowll

The posthumous papers of Rebecca MacKenzie document her adventures, along with her brother Doug, in 1920s China as the teenaged siblings are sent to live aboard their uncle's ship where they become involved in the dangerous activities of a mysterious secret society called the Honourable Guild of Specialists.
The setting is 1912-1928 China.

In the spring of 1920, teenaged siblings Rebecca and Doug MacKenzie continue their adventures on their uncle's ship, sailing through a typhoon into the Celebes Sea in pursuit of a missing "gyrolabe" which may be connected to the disappearance of their parents.
The setting is 1912-1928 China.

Siblings Becca and Doug discover important clues to their missing parents' expedition route and the location of Ur-Can, the fabled Storm City, and they embark on a perilous journey to the Takla Makan desert, racing against their uild enemies by steam train, riverboat, and airship across the Himalayas, trying to save not only their parents, but the entire planet.
The setting is 1912-1928 China.