In Dianne Freeman’s charming Victorian-era mystery series, Frances Wynn, the American-born Countess of Harleigh, finds her sister’s wedding threatened by a vow of vengeance.     London is known for its bustle and intrigues, but the sedate English countryside can host—or hide—any number of secrets. Frances, the widowed Countess of Harleigh, needs a venue for her sister Lily’s imminent wedding, away from prying eyes. Risings,...