Confession: I love switched-identity plotlines. Maybe it's my desire to have a twin/doppelganger, but I just like twins-switching-identities plots. Is it any wonder that I like Georgette Heyer's False Colours? (And yes, you must use the British spelling because it's so much more awesome.)
This is a re-read for me. I wanted a comfort read and this is definitely one. It's a caper with a happy ending for everyone.
Here's the plot: Kit and Evelyn are (male) twins. Kit, who serves on diplomatic missions, comes home to England because he senses his twin is in trouble. He's right; Evelyn is missing--and moreover, Evelyn is supposed to meet his soon-to-be-fiancee's family. Kit's mother convinces Kit to fill in just for that one night--the marriage is a society marriage and the couple barely know each other.
Basically, Kit get thrown in a masquerade and must spend oodles of time with his twin's fiancee. And you can guess what happens then...
It's a classic Heyer novel; you won't be disappointed if you pick it up. It's funny, a delight to read and one of her lighter works.