A young English boy and his family sublet an apartment in New York City on the condition that they take care of the owner's prized Siamese cat, but suddenly the cat disappears.
When their father is jailed for tax fraud, no one else seems to care much, but fifteen-year-old Betsy and her younger brother Roddy are determined to prove his innocence.
Two girls, each a "problem" to her family, arrive in Istanbul where they are soon involved with gypsy fortune tellers and the loss of a valuable horn-shaped pin.
Chris and Ken Arrow, who often accompany their anthropologist mother on her travels, find themselves pursuing a band of thieves through the back alleys and waterways of Hong Kong.
When they move into an old house in Seattle, the six Evans children discover a strange message, left by children who lived there thirty years earlier, that leads them on a treasure hunt.
