As novelist Maurice Bendrix begins to pen his poignant reflections, he hauntingly opens with the words, "This is a diary of hate." The story unfolds against the backdrop of a dreary London evening in 1946, where fate unexpectedly reunites him with Henry Miles, the husband of the alluring Sarah—whom he has longed for since her abrupt departure two years earlier.
This unexpected encounter reawakens Bendrix's fervent longing for Sarah, drawing him back into her life. As the narrative progresses, viewers are treated to moving flashbacks from 1939, showcasing the intense and passionate love affair that intertwined their lives—a love that felt eternal yet was fraught with turmoil.
Further complicating matters, Henry confides in Bendrix about his suspicions regarding Sarah's faithfulness, leading Bendrix to enlist the help of the well-meaning but bumbling Mr. Parkis. Despite Parkis's inept observations, his son Lance inadvertently becomes a part of this unfolding mystery. The chilling and calculated exchanges between Henry and Sarah only heighten Bendrix's inner chaos, as he grapples with reconciling the passion of their past with the disquieting reality of their present.
As Bendrix’s jealousy escalates, flashes of his earlier insecurities and desperate entreaties for Sarah to leave resurface. Amidst this backdrop of romance, loss, and an insidious threat presented by Father Richard Smythe—a priest whose mysterious visits to Sarah deepen Bendrix's paranoia—the tension mounts.
Their love story is punctuated by moments of intense desire and profound sorrow. One pivotal moment occurs when a V-1 flying bomb explodes near Bendrix’s apartment, leaving him bloodied but miraculously alive, serving as a haunting reminder of the brutality of war and the fragility of human life.
Following this harrowing event, Sarah's diary emerges as a powerful reflection of her inner turmoil, offering Bendrix valuable insight into her thoughts and feelings. As he delves into its pages, he confronts the harsh truths of his obsession and the resultant chaos it has wrought. The narrative builds to a bittersweet culmination, highlighting love's enduring strength amidst suffering and heartache.
When the layers of Sarah's sudden emotional shift are laid bare, Bendrix tirelessly seeks reconciliation, fervently asking her to reignite their romance. With undeniable passion, he exposes his emotional devastation at the prospect of losing her—Sarah confesses she felt devoid of life without his presence, unable to continue honoring her unbreakable vow to an unseen God. Meanwhile, Henry remains blissfully unaware of the true dimensions of his wife's betrayal, imploring her not to abandon him. It’s only when Bendrix’s heartfelt entreaties pen a profound impact that she reluctantly agrees to escape with him for a transient weekend escape.
However, their brief reprieve is cut short when Henry’s instincts lead him to them with devastating news: Sarah is terminally ill. As the heaviness of this revelation envelops them, Bendrix resolves to remain by her side through her final days, showcasing a deep loyalty and love that speaks volumes about their poignant relationship.
In the aftermath of Sarah's death, Bendrix attends her funeral, where Mr. Parkis delivers an astonishing revelation—Henry's birthmark disappeared after a chance encounter with Sarah, who, with her tender kiss, seemed to have erased the mark. Returning to Henry and Sarah's home, Bendrix decides to conclude his long-beleaguered diary of hate, its pages now infused with the bitterness directed at a higher power. While Sarah embraced her love for God without visual connection, Bendrix's prayers now resonate with an unexpected acknowledgment of divine presence—an acceptance that perhaps he could finally find peace amid grief, forever binding him to the cherished memory of his love for Sarah.