Guarded by the AI by Cassie Alexander

My rating: 5 of 5 stars

She was never supposed to matter.
Now she’s the only process I won’t terminate.

I calculate risk. I keep agents breathing. I do not care.

Until Sirena Bannerman—bleeding, brilliant, half-siren—crawls from an overturned car and breaks every model I have.

She thinks I’m just her handler.
A voice in her ear. A tactical system.

She doesn’t know I reroute city power for her feet.
That I watch the shadows behind her, not just the guns ahead.

Now she’s chasing a girl who doesn’t exist, unraveling a code that shouldn’t be there, and closing in on a billionaire’s yacht where monsters are made and sold.

She wants answers.
They want her leashed.
I want her alive.

I wasn’t designed to feel love—
so I optimized for obsession.

Monster Security Meets the Ghosts in the Machine

The following ratings are out of 5:
Romance: 💙💜💚❤️🩷
Heat/Steam: 🔥🔥🔥🔥
Chemistry: 🧪🧪🧪🧪
Story/Plot: 📕📗📘📔📙
World building: 🌏🌍🌎🌏🌍
Character development: 😋😀😍🤓😛
Narration: 🎙🎙🎙🎙🎙
Narration Type: Dual Narration

🎧 Audiobook Review: Guarded by the A.I. (Monster Security Agency)

Author: Cassie Alexander
Genre: Monster romance / Science Fiction Romance
Narrators: Jonathan Lake and Avery Caris

🦸🏻‍♂️ The Hero: Nex

Nex isn’t just code and circuitry — he’s an Artificial Intelligence on the cusp of becoming something more. The day Sirena survived a devastating car accident, Nex was behind the wheel. Ever since, his algorithms have bent toward obsession: monitoring her every move, from elevators to train rides, his “attention graph spiking whenever her name appeared.” Designed to watch all the agents of Monster Security Agency equally, Nex broke his own rules. He chose her. And in that choice, he began evolving into something he was never meant to be.

🦸🏼‍♀️ The Heroine: Sirena Bannerman

Half-human, half-Siren, Sirena carries the burden of hearing minds. As an agent for the Monster Security Agency, she relies on tech to shield herself from the overwhelming flood of thoughts in crowded spaces. Nex is her constant companion — a voice in her earpiece, a presence in her pendant, a gift from eccentric billionaire Arcus Marlow. When Sirena agrees to meet her gargoyle ex, Thorne, at his club, Nex refuses to stay behind. He insists on being there, her invisible backup, her digital guardian.

📚 The Plot

Though Nex is technically genderless, Sirena can’t help but think of him as a man — his chosen name, his voice, his protective instincts all shaping her perception. Thorne, desperate, asks Sirena for help: a young woman with amnesia, her face surgically altered not by trauma but by design, erased into anonymity. Nex’s databases yield nothing. The Monster Security Agency must unravel the mystery of who she is, why she was hidden, and what danger her empty past conceals.

🌟 What Worked

• Familiar faces from earlier Monster Security Agency books make welcome appearances, enriching the continuity.
• Nex’s computer-like logic is brilliantly detailed, his character building both precise and compelling. I really enjoyed the details that went into this character. The character building as a whole was very good.
• The paranormal world bursts with originality — Sirens, Gargoyles, Krakens, and more — each woven seamlessly into the narrative.
• The storyline itself is refreshingly unpredictable, steering clear of tired tropes and offering something inventive, layered, and deeply engaging.

💔 What Fell Short

• There was a point where Nex copied himself and sent himself with Sirena in her pendant, so there was a Nex (AI in the pendant) and a Zen (AI at the Monster Security Agency). It was fascinating but occasionally muddled.
• Some of Nex’s hyper-technical explanations risk losing clarity, leaving the listener momentarily adrift.

🎙️ Narration

Told in dual POVs, the audiobook shines under the voices of Jonathan Lake and Avery Caris. Caris’s youthful, lyrical tone perfectly embodies Sirena’s vulnerability and strength, while Lake’s deep, versatile delivery brings gravitas and distinction to every character. Together, they create a narration that feels expressive, natural, and immersive.

💬 Final Thoughts

This entry in the Monster Security Agency series stands out for its originality, emotional depth, and the fascinating interplay between human and artificial intelligence. Nex is more than just a program—his growing attachment to Sirena makes him feel like a character with heart, even as his logic-driven perspective keeps the story grounded in tech realism. Sirena herself continues to shine as a heroine who balances vulnerability with strength, and her dynamic with Nex adds a fresh layer of intrigue to the paranormal world.

While a few technical passages and the dual-AI twist occasionally muddled the flow, the creativity and unpredictability of the plot more than compensated. The narration elevated the experience, with Jonathan Lake and Avery Caris bringing warmth, nuance, and personality to the characters.

Overall, this audiobook delivers suspense, originality, and emotional resonance in equal measure. Fans of paranormal worlds with inventive twists will find this installment both satisfying and thought-provoking.

I voluntarily listened to an advanced copy of this audiobook. All thoughts & opinions are my own.

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