Raenalla Quietsong was a Harper spy stationed in Zhentil Keep. Shortly after the Zhentarim returned to the city in full force in 1370 DR, she was caught by the organization's High Lord Fzoul Chembryl, who had her permanently polymorphed into a harp.
Despite being a harp, Raenalla fully retained her mental faculties, and could perceive her surroundings and the passage of time. However, her transformation barred her from acting in any way, including speaking or using magic.
Fzoul Chembryl kept the transformed Raenalla in his private chamber in the Temple of Bane. She was a prized possession of his, and he would furiously retaliate against anyone who would free her from her transformation.