Elfshadow (Forgotten Realms: The Song & Sword Series Book 1) by Elaine Cunningham

Arilyn Moonblade is a Harper Agent with the reputation of one of the best Assassins in the realms. Everywhere she has been recently another member of the Harpers has been killed by someone who has come to be known as the Harper Assassin. Different factions with in the Harpers have different opinions of the situation some think she may be the target while others think she is the assassin. She must prove her innocence and the secret to unravelling the mystery depends on her finding the secrets of her Moonblade and her past. She is aided by the young Waterdhavian nobleman Danilo Thann a buffoon who dabbles in magic and music to disastrous effect.

This series is among my favourite and most read books. This book is not the best book in the series but has you engrossed in the story and constantly smiling/laughing at Danilo's antics. I personally thing Danilo is one of the greatest fantasy characters his duel persona of Dilettante nobleman failure and the powerful, intelligent and effective Harper agent.