Title :
Trixie Belden and the Mystery in Arizona

Author :
Julie Campbell

First Published :
1958

Chapter Titles :
1.  An Invitation
2.  The Big Question
3.  All Aboard!
4.  A Doubtful Welcome
5.  Trixie Solves a Problem
6.  A Dark Stranger 
7.  Trixie Is Suspicious
8.  Sobs in the Night
9.  Calamity Jane
10. Petey's "Day-Mare"
11. More Mysteries
12. "Madhouse!"
13. Cowboys and Questions
14. Lady Astorbilt
15. Tenny Tells All
16. In the Op'ry House
17. Swing Your Partner
18. Petey Tries Again
19. Dark Deductions
20. Surprise for Mr. X
21. A Dream Come True

Setting :
Sleepyside, New York and Arizona

Synopsis :
The Bobwhites head to Arizona to spend Christmas at Di's uncle's ranch.  However, when they arrive they find that the staff have disappeared and they have to return on the next plane.  But Trixie volunteers the Bobwhites to replace the staff and she tries to find out why the staff disappeared so suddenly and why some of the guests and the remaining staff are acting so mysteriously. 

Characters : 
Trixie Belden
Jim Frayne - newly adopted son of the Wheeler's
Honey Wheeler - Trixie's best friend
Brian Belden - Trixie's eldest brother
Mart Belden - Trixie's "almost twin" brother
Diana Lynch - a classmate and neighbour
Mrs Belden - Trixie's mother
Peter Belden - Trixie's father
Bobby Belden - Trixie's six year old brother
Miss Trask - Honey's governess
Tom Delanoy - the Wheeler's chauffeur
Mr Lynch - Diana's father
Monty Wilson - Diana's uncle
Maria - the ranch cook
Petey - Maria's son
Rosita - the ranch maid
Lionel "Tenny" Stetson - the ranch "cowboy"
Mrs Sherman - a ranch guest
Jane Brown - a ranch guest
Mr Wellington - a ranch guest
Sally Wellington - his daughter
Bob Wellington - his son
Billy Wellington - his son

Villains :
There weren't any!

Points of Interest:
This was Campbell's last book and again the mystery was a little weak.  Was this perhaps a sign of Campbell's waning interest in the series?  Thus ten years after Campbell published the first book in the series, her last book was published.