The Season by Sarah MacLean
From Amazon.com: "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!"
Um, yeah, you had me at "Regency England." I love pretty much anything from that time period. In case you don't believe me, I just bought the whole series of Jane Austen movies that showed on Masterpiece Theater last year. Yeah, I'm that obsessed...
The Season will be released on March 1st, but appears to be currently available for order on Amazon.com: