The title 'Siren Song' refers to the symbolic use of 'sirens' as an SOS signal between the DeWitt sisters, Simone and Devon. It originates from a traumatic childhood event where their mother tried to kill herself and Simone by filling their car with exhaust smoke. The sirens of the police arriving after Devon raised the alarm became imprinted in Simone's consciousness, turning 'sirens' into their code for seeking help. This theme is central to the episode and the series, highlighting the sisters' struggles and calls for rescue.

In episode 5, Simone finds herself trapped in an impossible and tragic situation. She is caught between two difficult choices: staying with her father, who poses a threat given his past, or choosing to be with Peter, which she perceives as the safer option for now. This moment is emotionally charged, especially in the police station scene where her father gently tells her it will be just them again, underscoring the danger Simone faces. The episode leaves viewers with a strong desire to save Simone, emphasizing her vulnerability.

Peter is portrayed as the real villain of the miniseries by the end of episode 5. He is involved in controlling and manipulating situations, including having a prenup with Kiki that influences her behavior. Ultimately, Peter ends up with Simone, and his actions are central to the tragic dynamics affecting the women in the story. The episode paints him as a figure who contributes to the suffering and difficult choices faced by the female characters.

The relationships among the women, particularly between Simone, Devon, and Michaela, are complex and fraught. Michaela is shown to let go of Simone too easily despite claiming closeness, which contrasts with Devon's evident sadness and concern for Simone. Devon and Kiki also share a moment of understanding on the ferry, realizing they misjudged each other and have more in common than they thought. These interactions highlight themes of misunderstanding, misjudgment, and the emotional toll on the women involved.

The finale is described as sad and tragic but also brings the story full circle, wrapping up loose threads. It leaves an ambiguous and poignant feeling, especially regarding Simone's fate and the sisters' relationships. The ending emphasizes the theme that the women often get the short end of the stick, with Peter as the antagonist. The episode closes with a sense of resignation and acceptance of new life paths for the characters, while maintaining emotional depth and complexity.