Title: Barbie
Subtitle: The Mystery of the Lost Valentine (Barbie Mystery Files, #5)
Description: (From the back cover)

Long-lost love...

Barbie and Kira are visiting Kira's aunt Emma for Valentine's Day! Then Emma starts receiving mysterious letters in the mail. They're love letters and they're over 50 years old. But who is sending them? It's up to Barbie and Kira to solve the mystery of the long-lost love letters!
Subjects: Juvenile fiction, Detective and mystery stories, Children's fiction, Barbie (fictitious character), fiction, Mystery and detective stories
People: Barbie