Here's the order of the books in the series:
1. The Face on the Milk Carton (1990)
2. The Note in the Box (1992)
3. The Secret in the Shadows (1993)
4. The Whisper in the Attic (1994)
5. The Diary in the Trunk (1995)
6. The Message in the Mirror (1996)
7. The Clue in the Closet (1997)
8. The Code in the Corner (1998)
9. The Key in the Keyhole (1999)
10. The Riddle in the Rain (2000)
11. The Secret in the Storm (2001)
12. The Warning in the Walls (2002)
13. The Mystery in the Mirror (2003)
14. The Truth in the Tears (2004)
15. The Choice in the Chamber (2005)
16. The Answer in the Ashes (2006)
17. The Dream in the Darkness (2008)
18. The Ghost in the Gallery (2009)
19. The Hope in the Shadows (2010)
20. The Truth in the Tower (2011)
21. The Light in the Labyrinth (2013)
22. The Promise in the Pines (2015)
23. The Secret in the Sanctuary (2017)
24. The Memory in the Mist (2019)
25. The Heart in the Harbor (2021)
The series follows the adventures of Janie, a young girl who discovers that she is actually a missing child named "Jenna" who was kidnapped years ago. The series explores the challenges of finding her real family, dealing with the trauma of her abduction, and learning to navigate her new life.