Simone wakes up abruptly from a nightmare in Devon's guesthouse, visibly shaken and disoriented. Devon notices Simone's distress and tells her she had a severe panic attack during the night. Simone struggles to regain composure, revealing her ongoing battle with anxiety and trauma. Devon tries to comfort her, but Simone remains tense and withdrawn, indicating the depth of her internal turmoil.

Later, Simone confronts her sister Kiki about their strained relationship and the secrets between them. Kiki asks Simone if there is anything she is hiding, to which Simone replies "No," though it is clear she is withholding the truth. This moment underscores the growing tension and mistrust between the sisters, setting the stage for future revelations.

Simone is then fired from her job, a blow that leaves her emotionally devastated. She appears almost lifeless, as if a part of her has died inside. This firing marks a turning point for Simone, pushing her into a darker emotional state. Her father informs her that they will be moving, which adds to her sense of instability and loss.

As the episode progresses, Simone begins a new romantic relationship with Peter, a man who also struggles with panic attacks. This connection is significant because it mirrors Simone's own vulnerabilities and past trauma. Their relationship develops quietly but with an undercurrent of complexity, hinting at future complications.

Devon, observing Simone's transformation, starts to suspect that Simone might be the true "monster" in their story, rather than Kiki as she had previously thought. Devon is horrified by the changes she sees in Simone, who seems blinded by the allure of wealth and power. This shift in perception highlights the episode's theme of blurred lines between victim and perpetrator.

In a climactic scene, Simone reveals her new relationship with Peter to Kiki, signaling a decisive break from her past and a step into a more dangerous path. Devon watches this exchange with shock and disbelief, realizing that Simone has embraced a version of herself that is ruthless and driven by ambition.

The episode ends with Devon grappling with the reality of who Simone has become, leaving the audience with a sense of foreboding about the consequences of Simone's choices and the true nature of the "monster" in their midst.

The episode "Monster," the third in Sirens Season 1 Limited Series (2025), ends with Devon deciding to return to her life as caretaker for her ailing father, accepting that her sister Simone has chosen a different, darker path by aligning with Peter and Michaela. Michaela and Devon leave the island together, sharing a moment of mutual understanding that none of the women are truly monsters, despite appearances. Simone remains on the island, poised to become the new lady of the house, symbolically standing on a cliff like a mythological siren, suggesting the cycle of manipulation and tragedy will continue.

Expanded narrative of the ending scene by scene:

The climax unfolds at Michaela's annual Labor Day charity gala, where tensions reach a boiling point. Devon confronts Michaela publicly, accusing her of having a hand in the disappearance of Peter's first wife, Jocelyn. Michaela reveals the truth: Jocelyn did not die mysteriously but became a recluse after a disfiguring plastic surgery following her divorce from Peter. This revelation deflates the rumors and shifts the narrative around Michaela's character.

The biggest shock comes when Peter announces he is divorcing Michaela and moving in with Simone, exposing his true nature and leaving Michaela isolated. This moment underscores Peter's pattern of using and discarding women, highlighting his selfishness and instability.

Following this, Devon makes a pivotal choice. She decides not to stay on the island or pursue the luxurious life Simone seems to want. Instead, she boards the ferry back to New York to resume her role as caretaker for their ailing father. This decision marks Devon's acceptance of her responsibilities and a conscious step away from the toxic dynamics on the island.

Michaela, now divorced and stripped of her status, leaves the island with Devon. Their ferry ride is quiet but meaningful; they discuss the events that transpired and share a moment of empathy. Devon tells Michaela she doesn't believe she is a monster, and Michaela reciprocates the sentiment about Simone. This exchange humanizes all three women, challenging the notion that any of them are inherently evil.

The final scene focuses on Simone, standing alone on the cliff of her newly acquired estate. The wind blows through her hair as she gazes out over the ocean, bathed in golden sunset light. Ominous music plays softly, evoking the myth of the siren. Simone's posture and expression suggest she is ready to embrace her new role as the island's "monster," the new lady of the house who will likely continue the cycle of seduction and destruction that Peter has perpetuated.

In terms of character fates:

• Devon returns to Buffalo to care for her father, choosing a more grounded and responsible life, though she buys a home nearby to maintain some independence.

• Michaela loses her marriage and social standing but leaves with Devon, her future uncertain but possibly involving a return to her legal career.

• Simone stays on the island, poised to marry Peter and take over the role Michaela once held, becoming the new "monster" in the cycle of manipulation.

• Peter continues his pattern of using women to fill his own void, moving on from Michaela to Simone, suggesting the cycle will repeat.

This ending scene by scene captures the unraveling of relationships, the exposure of hidden truths, and the choices each woman makes in response to the toxic environment around them, culminating in a haunting visual metaphor of Simone as a modern siren ready to lure the next victim.

The episode "Monster," which is episode 3 of the 2025 limited series Sirens season 1, does not have a specifically noted post-credit scene in the available detailed summaries or reviews. The sources focus on the episode's main plot developments and the series' overall ambiguous and emotionally complex ending but do not mention any additional scene after the credits in this particular episode.

Therefore, based on the current information, there is no confirmed post-credit scene for Sirens season 1 episode 3 "Monster."

The TV show Sirens, season 1 episode 3 titled "Monster" (2025), is rated TV-MA and is not considered family friendly for children or sensitive viewers. It contains mature themes including suicide (carbon monoxide poisoning), offensive language, and sexual content.

Potentially upsetting or objectionable aspects include:
- The revelation of a character's mother dying by suicide, which is handled with emotional weight and could be distressing.
- Some scenes involve sexual content and intimate relationships that may not be suitable for younger audiences.
- Use of strong language and possibly some intense emotional confrontations.
- Themes of power dynamics, manipulation, and psychological tension that might be unsettling for sensitive viewers.

Overall, the episode deals with complex adult themes and emotional drama, making it more appropriate for mature audiences rather than children or those sensitive to such content.