Dorothy Dale's Great Secret

This is the third book in the Dorothy Dale series, written under the house pseudonym of Margaret Penrose. "Girls have to have secrets, or they wouldn't be girls, and we have now got ours." In this, the third book in the Dorothy Dale series, written under the house pseudonym of Margaret Penrose, Dorothy proves herself to be a good friend to Tavia. Amid suspicion and worry for her chum, she undertakes the perilous task of 'rescuing' her and saving her reputation with minimal help from her cousins Nat and Ned White and without spreading her concerns, in the hope they be unfounded. (Summary by Lynne Thompson)
Books in this series:

Dorothy Dale: A Girl of Today (1908)

Dorothy Dale at Glenwood School (1908)

Dorothy Dale's Great Secret (1909)

Dorothy Dale and Her Chums (1909)

Dorothy Dale’s Queer Holidays (1910)

Dorothy Dale’s Camping Days (1911)

Dorothy Dale’s School Rivals (1912)

Dorothy Dale in the City (1913)

Dorothy Dale’s Promise (1914)

Dorothy Dale in the West (1915)

Dorothy Dale’s Strange Discovery (1916)

Dorothy Dale’s Engagement (1917)

Dorothy Dale to the Rescue (1924)