The Mystery of the Dancing Angels (Three Cousins Detective Club)

is #4 in the Three Cousins Detective Club series.
==Book Description==
In The Mystery of the Dancing Angels, Sarah-Jane Cooper has to baby-sit her pesky cousin Patience when the three cousins visit an historic mansion. Taking care of an ordinary four-year-old is hard work, but taking care of Patience proves next to impossible! Then Patience disappears and reappears with a story about "dancing angels." Is it just another one of her silly tall tales? It’s up to the TCDC to find out!
(Description from paperbackswap.com)