The climactic episode of "Playing Nice" unfolds with Maddie and Pete arriving at their supervised visit with Theo, under the scrutinizing gaze of the Family Court Advisor. As they embark on this delicate encounter, everything proceeds smoothly until Theo reveals to Maddie, with an innocence that stings, that Lucy, not she, is his real mummy. Maddie's heart sinks, and her frustration mounts when the Advisor fails to document this emotional exchange, leading to an outbreak of anger that promptly terminates their session. Pete and Maddie are left with no choice but to depart, hearts heavy.
Anika, their lawyer, delivers the grim news: the Family Court Advisor's report paints them in a damning light following their turbulent visit with Theo. Yet, she offers a glimmer of hope by reminding them that this is merely one individual's perspective.
The day of reckoning arrives, and the child psychologist takes the witness stand first. He reveals that Theo exhibits signs of detachment, possibly rooted in heredity, but thrives in Maddie and Pete's nurturing environment. He also touches upon David's potential distress if separated from Lucy, while strangely omitting Miles from the discussion.
Next, Maddie and Pete face the court's scrutiny. The Lamberts' lawyer unleashes a relentless assault, targeting Maddie's choice to be a working mother and probing into her postnatal depression, twisting her words into weapons against her. Maddie responds with a heartfelt testament to her love for both boys, pleading for the court to recognize their right to be with her and Pete. However, Lucy and Miles' subsequent testimony undermines her efforts, their deceitful narratives weaving a tangled web of lies.
During a court recess, Miles confronts his estranged mother, Edith, with venomous contempt, ignoring her pleas and revelations about his past misdeeds. Unbeknownst to him, Lucy eavesdrops on this chilling exchange, her illusion of Miles' perfection shattered. Edith warns Lucy about Miles' true nature, urging her to reconsider her partnership.
That night, Lucy confronts Miles about his deceit, but he responds with threats and abuse, pinning her against the wall. As she complies with his demands, Lucy casts a surreptitious glance at the security camera, planning her next move.
The courtroom is transformed the next day by the presence of a TV screen, bearing an anonymous video that shows Miles giving Theo cannabis gummies—the incident that led to Theo's hospitalization. The court is dumbfounded, and Lucy feigns ignorance, suggesting a nanny might be the whistleblower. Pete and Maddie dare to hope for custody, but the judge orders an investigation into the poisoning, allowing Theo to return to them temporarily. The judge's order for Miles to vacate the Lambert home brings a fleeting smile of relief to Lucy's face, signaling a potential escape from her abusive spouse.
Pete and Theo's tranquil moment at the harbor is shattered when Theo disappears, sparking a panic-stricken search. Pete spots Theo's bright yellow coat with a stranger—Miles—and races to a secluded beach. The haunting sight of Theo's coat floating in the sea, mirroring the opening scene of the series, sends Pete diving into the waves in desperation. Finding only the coat, Pete emerges to confront Miles, who revels in his distress before Theo emerges from hiding, unharmed.
The police launch a search for Miles, but he evades capture. Maddie visits Lucy, who is stunned by the revelations and apologizes for Miles' actions. Maddie notices Lucy's bruises, revealing Miles' violence, and offers her support.
The next morning, Lucy awakens to find David missing and Miles casually drinking coffee. Forced into a picnic by Miles, Lucy secretly calls Maddie, whose ignored call leaves her in suspense until she listens to Lucy's voicemail, unveiling the true depths of Lucy's plight.
As Lucy's voicemail unfolds, revealing to Maddie her long-held fear of Miles, we witness a tense scene where Lucy exits a car in a secluded area, accompanied by Miles and David. Through the voicemail, Lucy unfolds a narrative of Miles' increasingly controlling behavior, which escalated during her pregnancy, painting a picture of a man capable of hurting those he loves. With a trembling voice, she confesses her deepest dread—that Miles might commit something truly heinous.
Driven by this dread, Lucy admits to a stunning revelation: she swapped the babies in the NICU to shield her son from growing up under Miles' shadow. Upon witnessing Pete's kindness as he cared for what he believed was his son in the hospital, Lucy felt confirmed in her decision to protect her child and gift him a nurturing family. With a heavy heart, she vows to always safeguard David and apologizes to Maddie, professing her unwavering love for David.
Maddie, tears streaming down her face, sits in the car absorbing the gravity of Lucy's confession. As the voicemail concludes, Lucy discloses that Miles is present and they are being taken somewhere. Simultaneously, Miles guides Lucy and David along a perilous cliff edge, where Lucy, in secret, shares their location with Maddie.
Confronted by Lucy about being the one who sent the incriminating video to the court, Lucy initially tries to blame the nanny, but Miles isn't convinced. He grabs David, standing precariously on the cliff's edge, his actions sending shivers of terror through Lucy. Miles pretends to throw David off, forcing Lucy to confess her guilt. Meanwhile, Maddie discovers their abandoned car and races to their location.
Desperate to rescue David, Lucy offers Miles a deal: she will give David to Maddie and Pete, allowing them to raise Theo. It's a sacrifice she loathes but knows it's what Miles wants to hear. However, Miles rejects her offer, insisting he doesn't need her or David and vows to raise Theo alone. Just as it seems they're all doomed to plummet over the cliff, Maddie's voice pierces the tension, distracting Miles momentarily. Seizing the opportunity, Lucy grabs a rock and strikes Miles over the head. Maddie snatches David to safety, while Miles begins to slip, dragging Lucy with him. In a final act of defiance, Lucy frees herself and pushes Miles, sending him to his demise.
Later, Maddie assists a shaken Lucy in washing the blood from her hands at her home. Lucy expresses relief that with Miles gone, she can finally breathe easy. She hesitantly asks for forgiveness for swapping the boys at birth, and Maddie, understanding her motive to shield her son from Miles, offers her understanding.
The police soon arrive, followed by Pete, at Miles and Lucy's house. They collectively weave a tale of Miles' distressed state, his angry departure, and a presumed suicide at the coast.
The episode then skips forward three months, revealing Pete and Maddie joyfully playing on the beach with Theo, their family once again united in happiness. As Maddie glances behind her, she sees Lucy sitting on the beach, playfully engaging with David. While it remains ambiguous who has custody of the boys, it's assumed that Lucy, Maddie, and Pete have reached a consensus, ensuring both boys receive frequent visits from all.
As the episode draws to a close, Maddie fixes a serious gaze on Lucy, which softens into a smile as their eyes meet. However, her gaze turns serious once again as she looks out to sea, burdened perhaps by the magnitude of their lie to the police and the events of the past three months.
