The Season by Sarah Maclean
Seventeen year old Lady Alexandra is strong-willed and sharp-tongued -- in a house full of older brothers and their friends, she had to learn to hold her own. Not the best makings for an aristocratic lady in Regency London. Yet her mother still dreams of marrying Alex off to someone safe, respectable, and wealthy. But between ball gown fittings, dances, and dinner parties, Alex, along with her two best friends, Ella and Vivi, manages to get herself into what may be her biggest scrape yet.
When the Earl of Blackmoor is mysteriously killed, Alex decides to help his son, the brooding and devilishly handsome Gavin, uncover the truth. But will Alex's heart be stolen in the process? In an adventure brimming with espionage, murder, and other clandestine affairs, who could possibly have time to worry about finding a husband? Romance abounds as this year's season begins!
I'm aware this is already out in America but alas here in the UK it's not out 'til June. I can't wait to read it because I love historical fiction, especially Regency romances, and (this is superficial) I love the cover! It reminds me of The Luxe by Anna Godbersen, but better because it seems less focused on social-standing, and of course it's set in London!