Without a Summer by Mary Robinette Kowal, Tor 2013.
I've reviewed the other entries in the Glamourist Histories series (Shades of Milk and Honey and Glamour in Glass), and this is a delightful third book.
Vincent and Jane are recuperating from their injuries during the Battle of Quatre Bras, where Napoleon was defeated, and Jane's younger sister, Melody (20), is beginning to despair of ever finding a husband. Vincent and Jane get a commission to do a glamural in London, and they decide to take Melody with them to be Out during the Season.
1816 was known as the Year Without A Summer. At the time, the link between volcanic eruptions and cooling wasn't known (remember 2010?), and it took much longer for news of volcanic eruptions in Indonesia to reach northern Europe. In Kowal's alternate historical world, people are blaming the continuing winter and the crop failures that result on coldmongers, a specialized type of glamourist who can make things cold. Typically, they keep groceries cool on the way home in summer or make ices in winter. The populace is dissatisfied, and they attack coldmongers in the street.
Vincent's estranged family invites him and Jane over for dinner. It is readily apparent why Vincent was pleased to become estranged from them.
Jane overhears their employer's son discussing plans to march on Parliament, and she (and Vincent) slowly unravel and become deeply entangled in a web of plots.
One recurring theme throughout the book is prejudice: against the Catholics, the Irish, the Irish Catholics, the Indians, the poor, coldmongers. It's very effective without being ham-handed.
If you read and enjoyed the other books in the series, you will enjoy this one as well. If you haven't read the others, and you enjoy Jane Austen or Georgette Heyer, what are you waiting for?