Kay Tracey is sixteen years old and lives with her mother and a cousin, Bill, who is a lawyer.  Her father is dead.  Her best friends are a pair of twins, Betty and Wilma Worth. She also has a rival, Ethel Eaton (called Chris Eaton in updated versions of the series), who is jealous of her reputation as a detective and attends the same high school she does.  Ethel/Chris frequently tries to interfere with her investigations.

This series was one of many created by the Stratemeyer Syndicate, the same writing group that produced the Nancy Drew series and the Hardy Boys series, among others. According to All About Collecting Girls’ Series Books by John Axe (2002), the books in the series were written by Mildred A. Wirt, the ghostwriter who also worked on the Nancy Drew series. In fact, she was working on Kay Tracey even while she was working on the Nancy Drew books, which may explain many of the similarities between the two series. Each of the series features a girl detective with only one living parent who lives with a lawyer and who has two best friends with two different hair colors and somewhat opposite personalities and interests who accompany her on her adventures. Although Kay is described as a brunette in the books, she is often shown as a blonde on covers of books, like Nancy Drew, who is generally considered to be blonde or red-haired, depending on the book, with authors sometimes trying to reconcile the discrepancy by saying that she’s strawberry blonde. The stories in the series are somewhat formulaic, often featuring spooky old houses and people who are trying to cheat someone else out of a treasure or an inheritance.

Like Nancy Drew, Kay Tracey also never ages throughout the series. In early Stratemeyer Syndicate series, characters did age throughout their series, and kids would grow up, get married, and eventually have kids of their own. By the time Kay Tracey was developed, the Syndicate had decided to keep its characters frozen in age because, when characters grow up and age, eventually, the series has to come to an end. If characters never age, a series can continue indefinitely.

Like other Stratemeyer Syndicate series, Kay Tracey, which originally started in the 1930s, was updated and reissued in the 1950s. Books in the series have been reissued multiple times between 1951 and 1984 under different publishing companies, and different publishing companies have published the books in different orders. In fact, some publishing companies only reissued some of the original 18 books in the series instead of reprinting the series in its entirety. The order of the books doesn’t particularly matter because the characters do not age across the series and each book can be read as a standalone. Previous adventures do not have any effect on later books in the series or explain anything about other characters’ origins that would be require some books to be read before others.

Because it would take too much time to explain the order of the books with each reissue, I’m going to list the full series as it was originally published. However, individual reviews of these books may show different book numbers from this list, and I’ll have dates of the book printings as well as the original copyright dates.

Books in the Series:

#1 The Secret of the Red Scarf (1934)

Kay attempts to help a young man with amnesia, who only remembers that he is trying to find his sister, Helene.  Strangely, he insists that his sister looks very much like Kay.

#2 The Strange Echo (1934)

While Kay is out on Lost Lake, a mysterious voice calls to them to turn back.  Who wants to scare people away and why?

#3 The Mystery of the Swaying Curtains (1935)

Kay’s friend, Sissy, was adopted, but now she learns that she may actually be an heiress.  Is it true and can Kay help her prove it?

#4 The Shadow on the Door (1935)

Kay is concerned about a client of her cousin, who is a lawyer.  The woman’s decisions appear to be influenced by a mysterious stranger.

#5 The Six-Fingered Glove Mystery (1936)

Kay searches for a movie star who has been kidnapped.

#6 The Green Cameo Mystery (1936)

When Kay attempts to warn a friend about a medium’s fakery, the medium threatens Kay with a curse.  Soon, bad things start happening to Kay, and the friend’s daughter disappears.

#7 The Secret at the Windmill (1937)

When someone steals something that Kay was guarding, she has to recover it, not only to save her reputation, but a friend’s wedding!

#8 Beneath the Crimson Brier Bush (1937)

Kay finds an abandoned baby girl.  Then, Ethel mysteriously disappears, and her mother asks Kay to find her.

#9 The Message in the Sand Dunes (1938)

Kay manages to stop someone from robbing the house of the eccentric Crowley sisters, but who was the mysterious burglar and what did he want?

#10 The Murmuring Portrait (1938)

A spooky portrait of a gypsy may hold the key to finding the heir to a fortune.

#11 When the Key Turned (1939)

Kay tracks down the thief who stole a priceless Stradivarius belonging to the family of a friend.

#12 In the Sunken Garden (1939)

Kay investigates a mysterious person who looks exactly like her.

#13 The Forbidden Tower (1940)

While on vacation in Florida, Kay and her friends investigate the mysterious disappearance of Emily Dodd.

#14 Sacred Feather (1940)

Kay investigates a fire at the local library and the mysterious people who were trying to steal art objects from the burning building.

#15 The Lone Footprint (1941)

Strange things are happening at a summer resort where Kay is staying.  Things disappear, fires break out, and mysterious voices call out in the night.

#16 The Double Disguise (1941)

Kay investigates the theft of a secret formula.

#17 The Mansion of Secrets (1942)

Kay spots a mysterious figure attempting to remove something from underneath a stair in a mysterious old mansion.

#18 The Mysterious Neighbors (1942)

Kay and her friends set off on a houseboat trip, only to be told that their boat is jinxed.  Mysterious signals at night and a gang of jewel robbers complicate their simple vacation.