Trixie glanced behind her.  Harrison's derby hat sat neatly in the exact middle of the backseat.  It looked as dignified and as correct as its owner.

"Why was Di so anxious about it?" she asked.

"Oh, you know Di," Jim answered vaguely.  "I think she just wanted to show the rest of the staff that she was able to look after everything.  I can understand it."

Trixie frowned.  "Well, I don't understand it at all.  It's not like Di to be so bossy."

"Maybe, Trix," Jim said gently, "it's because you're so used to running things yourself."

"But I'm not bossy," Trixie cried.

Jim grinned at her to take the sting out of his words.  "Oh, sometimes you are.  Just a little bit, maybe.  But then, I guess someone's got to be the boss."

Trixie wasn't sure she liked this thought at all.

"I thought we were all bosses," she said slowly.

Jim decided to drop the subject.

The Mystery of the Headless Horseman (p. 114-115)

Title :
Trixie Belden and the Mystery of the Headless Horseman

Author :
Kathryn Kenny
The ghost writer of this book is thought to be Joan Chase Bowden.

First Published :
1979

Chapter Titles :
1.  A Mysterious Disappearance
2.  The Search
3.  Trixie's Monster
4.  To the Rescue
5.  Curiouser and Curiouser
6.  The Missing Vase 
7.  The Phantom Rider
8.  The Horse Wore Socks
9.  Trouble Ahead
10. Derby Surprise
11. Trixie Is Worried
12. Disappointment!
13. The Phantom Rides Again
14. Bob-White Breakup?
15. Museum Mystery
16. "The Butler Did It!"
17. Trapped!
18. Triumph!

Setting :
Sleepyside, New York.

Synopsis :
The Bob-Whites plans for a fundraising Bazaar go awry when Harrison, Di's butler, goes missing.  The search leads them to Sleepyside Hollow where they find Harrison injured and locked in the cellar and Trixie suspects there is more to the story than he is letting on.  Her suspicions cause a rift between her and Di which widens as Trixie tries to find a missing vase and clear the name of a dead man.  Did the butler really do it, and can Trixie use a simple riddle and the mysterious alphabet trees to solve the mystery?  Or will she and Honey be frightened off by the headless horseman that rides the woods of Sleepyside Hollow?

Characters : 
Trixie Belden
Jim Frayne - 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 Bob-White and neighbour
Dan Mangan - a Bob-White and Regan's nephew
Helen Belden - Trixie's mother
Peter Belden - Trixie's father
Bobby Belden - Trixie's six year old brother
Miss Trask - Honey's governess
Harrison - the Lynches butler
Rose Crandall - the owner of Sleepyside Hollow and widow of Jonathan Crandall, former curator of the Sleepyside Museum.
Polly Ward - Rose's sister
Dr Ferris - Sleepyside doctor
Janet Gray - museum guide
Charlie Burnside - museum guard
Richard Parkinson - owner of the missing Ming vase
Alfred Dunham - acting curator of the Sleepyside museum

Villains :
Alfred Dunham - he stole the Lynches Lien-Ting and tried to steal the vase from the Bob-Whites at gun point.

Points of Interest:
Di, Honey and Trixie are said to be in the ninth grade, while Dan and Mart are sophomores and Brian and Jim are seniors (p. 18).

Regan must have received a promotion from groom to trainer: 'His uncle, Bill Regan, who was the Wheelers' horse trainer...' (p. 29).

Trixie refers to a mystery that Honey and the reader knows nothing about: 'Don't you remember?  We were here once before, quite a while ago.  We were tracking down a hot lead on one of our mysteries, but Brian took a wrong turn in his old jalopy.  We found ourselves on that little road down there.'  (p. 40)

The relationship between Di and Trixie is strained in this book as Di grows into a leader and Trixie doesn't like it:

'Trixie glanced at her sharply.  What was wrong with Di?  She had a funny lah-di-dah tone in her voice that Trixie had never heard her use before.  It was almost as if - that was it - as if Di was playing a part on the stage.

And the role she's playing is Lady Diana of the Lynch estate, Trixie thought.  She was not sure she liked it.'  (p. 51)

Trixie was a 'candy striper' but in #16 The Mystery of the Missing Heiress, she was a 'volunteen' (p. 132).

LOL!  Trixie accuses Jim of not noticing anything (p. 137).

Trixie has a bet with Mart that he can't train Reddy within a week.  They eventually work out that Reddy will do the opposite of what they tell him to do and Reddy saves the day when the Bob-Whites find themselves at gun point:
'Trixie had a sudden idea.  "Oh, Henry, forgive me!" she whispered.  Then in a loud voice she called, "Reddy!  Don't chase the cat!"
In one second, Reddy was in the room.  In another second, he had dashed between a pair of legs in dark trousers.
Their wearer didn't have a chance.  His legs shot out from under him just as his fingers were closing around the precious box.
"Get him, boys!" Brian yelled, diving for the gun.
Jim, Mart and Dan joyfully obeyed.  There were sounds of a loud scuffle on the floor.  Then there was silence.
From the top of a bookcase, Henry yawned and began to wash himself.  Reddy, who had not come anywhere close to catching him, looked bitterly disappointed' (p. 207-208).