The Clue in Blue

This is a lovely YA mystery, with the 16 years old Connie Blair in main role.
She's pretty, smart, grounded, rational girl with big dreams and ability to enjoy life and beauty.
She has a twin sister who wants nothing but stay in her small hometown, get married and have a normal life as a housewife in the late 40s, when this book was written, but Connie wants to be like her aunt, a career woman, and live in the city.
She gets a week's job as a floor model in a big department store where her aunt works as the stylist, and solves a mystery with international connections.

I thought it was exciting, interesting, and I want to read more about Connie's adventures in amateur sleuth world.