The Truth-Teller's Tale — Sharon Shinn

Innkeeper's daughters Adele and Eleda are "mirror twins"--identical twins whose looks are reflections of each other's--and their special talents are like mirrors, too. Adele is a Safe-Keeper, entrusted with hearing and never revealing others' secrets; Eleda is a Truth-Teller, who cannot tell a lie when asked a direct question. The town of Merendon relies on the twins, no one more than their best friend, Roelynn Karro, whose strict, wealthy father is determined to marry her off to the prince. When the girls are seventeen, a handsome dancing-master and his apprentice come to stay at the inn, and thus begins a chain of romance, mistaken identity, and some very surprising truths and falsehoods.