A young woman sits on a red cushion, her body turned slightly to the left while her gaze meets the viewer directly. She wears a white blouse with voluminous sleeves under a deep blue gown trimmed with gold, and a delicate halo hovers above her head. Her right hand rests on the hilt of a sword, its blade angled across her lap, while her left arm drapes over the top of a large wooden spiked wheel broken in several places.

A palm frond, the traditional symbol of martyrdom, lies diagonally across the foreground, partly beneath her feet and the cushion. The background is a deep, impenetrable darkness, setting off the figure's pale face and hands, which are illuminated by a strong, focused light that falls from the upper left. The textures of the fabrics are rendered with meticulous attention: the sheen of the blue drapery, the softness of the white linen, and the subtle patterns on the cushion are all visible.

The composition is tightly arranged, with the saint and her attributes filling almost the entire frame, and the broken wheel’s spokes and iron spikes forming a striking pattern behind her. Her expression is calm but alert, and her posture is both relaxed and dignified, suggesting both vulnerability and resolve. She is shown with her traditional attributes: the spiked wheel of her attempted execution, the sword used in her beheading, the palm of martyrdom, and the halo of sainthood. Caravaggio’s use of dramatic lighting and naturalistic detail places this work firmly within the Baroque movement. The painting’s close observation of the model’s features and the tactile presence of objects reflect the artist’s innovative approach to religious art.