The film intricately explores the tumultuous relationship of Mozhdeh and Morteza Samiei as they prepare for their upcoming vacation to Dubai, just after the Chaharshanbe Suri festival, which is celebrated on the eve of Wednesday preceding Nowruz. In a bid to tidy up their home, Morteza hires a new maid named Rouhi, a bride-to-be, through an agency. However, Mozhdeh is reluctant, believing that maid services are unnecessary.
As Rouhi gets to work, she begins to piece together the tension between Mozhdeh and Morteza. Mozhdeh becomes increasingly suspicious that Morteza is seeing their divorced neighbor, Simin, behind her back after discovering her phone number in the call logs. Simin has turned their apartment into a beauty salon, raising eyebrows among the neighbors who are already wary of her divorced status. With Morteza stating he won't return home until 5 PM, Mozhdeh tasks Rouhi—who expresses a desire to have her eyebrows trimmed—with asking Simin about her availability, which unfortunately confirms Mozhdeh's fears.
Simin manages to trim Rouhi’s eyebrows, during which Rouhi overhears that Simin is well aware of the Samiei's travel plans to Dubai. Just as Rouhi is leaving, the landlord approaches Simin, announcing that the apartment is on the market. Quick-thinking, Rouhi poses as Simin’s niece, preventing a potentially awkward confrontation. Upon her return to the Samiei household, Rouhi discovers that Mozhdeh has taken her chador to secretly spy on Morteza, while Rouhi is left to pick up Amirali, their son, from school.
Furious, Morteza finds out about Mozhdeh's actions and lashes out, leading to a public confrontation where he physically assaults Mozhdeh. Exasperated by the situation, Mozhdeh decides to leave with Amirali to stay with her sister and brother-in-law, refusing to listen to Morteza's apologies. In an effort to de-escalate tensions, Rouhi fabricates a story about why Simin is aware of their plans to leave.
In a twist, Morteza offers Rouhi a ride home under the condition that she accompanies him and Amirali to watch the fireworks. While separated briefly, he secretly meets with Simin, confirming their affair, only to find that she wants to end their relationship to avoid breaking up the Samiei family. Meanwhile, Simin finds herself lonely and harassed in public. Rouhi, having caught a whiff of Simin's perfume, begins to piece together the truth about Morteza’s betrayal, especially when she spots him with Simin’s distinctive musical lighter.
Later, while waiting for a ride, Rouhi sees Simin’s ex-husband dropping their daughter off, contemplating telling Mozhdeh but ultimately deciding against it. As Mozhdeh continues her cleaning and spying on Simin, Rouhi gets a ride home. When Morteza questions Rouhi about their earlier lies, she can only awkwardly respond that Simin had been pleasant. Morteza attempts to convince Simin’s ex-husband to come inside, but they decline, opting to sleep in their car. The night concludes with Morteza alone and Mozhdeh tucked in with Amirali.
