(CNN)Zoë Saldana plays an important and powerful role in a new music video for Sia.
In the video for "Free Me," released Thursday, Saldana plays a pregnant woman who learns she has HIV and must be treated so she can prevent the spread of the disease to her unborn child.
Through interpretive dance, viewers then follow the woman's emotional turmoil, with an ultimately hopeful ending.
Oscar-winner Julianne Moore lends her voice as the narrator.
Proceeds from the song, which is available for download and streaming starting Friday, will go toward supporting trials for an HIV vaccine through the Abzyme Research Foundation's #endHIV campaign, according to Sia.
The ballad is the latest new material to come from the singer in recent weeks.
Sia also lends her pipes to the soundtrack for "Wonder Woman," with a rallying tune called "To Be Human."