Cahit Tomruk is a Turkish German in his 40s. He has given up on life after the death of his wife and seeks solace in cocaine and alcohol. One night, he intentionally drives his car head-on into a wall and barely survives. At the psychiatric clinic where he is treated, a young woman named Sibel Güner approaches him, recognizing him as being Turkish-German. She asks Cahit to marry her, but he quickly declines. Cahit later realizes she is at the hospital after trying to commit suicide. He sees her interacting with her conservative family. Leaving the hospital to go get beers, Sibel confides that her brother broke her nose when he saw her holding hands with a man, and she is desperate to escape her family. When Cahit again declines to marry her, she stabs herself in the wrists with a broken bottle. The incident shakes him up, but Cahit decides to marry Sibel after all. He goes to her family pretending he saw her at the hospital and seeking their approval to marry her. Despite the disparity in their ages, Sibel's family agrees to the marriage. After Sibel tells him that she prefers an independent sex life, they live as roommates with separate private lives. They eventually fall in love. Problems mount after Cahit accidentally kills one of Sibel's former lovers in a confrontation. Cahit is sent to prison and Sibel, her infidelity exposed, is disowned by her family. While Cahit is in prison, Sibel goes to Istanbul to stay with her cousin Selma —a divorced woman who manages a hotel. Sibel takes a job as a maid in Selma's hotel, but finds her new life to be too restrictive. She leaves Selma's apartment to live with a bartender who provides drugs and alcohol. Eventually, he rapes her during her drunk sleep and throws her out. Roaming the streets that night, she is accosted by three men who eventually beat her up. One of them stabs her and they leave her for dead. Several years later, Cahit travels to Istanbul upon his release from prison, hoping to find Sibel. Initially, Selma refuses to tell Cahit where Sibel is, but later tells him that the younger woman is in a long-term relationship and has a daughter. Cahit waits in a hotel for Sibel's call. It eventually comes, and they meet to make love while her boyfriend is on a business trip. After their two-day tryst, Cahit asks Sibel to take her daughter and run away with him. She accepts the plan, but, while packing at home she hears her husband return and squeals of delight from her daughter. At the bus stop, Cahit waits but she never shows up. The film ends with Cahit on a bus, presumably traveling to Mersin, the city where he was born.
Head-On has received positive reviews from critics. On Rotten Tomatoes, the film has a "certified fresh" rating of 91%, based on 85 reviews, with an average rating of 7.3/10. The website's critical consensus reads, "A raw, provocative drama about star-crossed love and the lives of immigrants caught between the traditional and modern." On Metacritic, the film has a score of 78 out of 100, based on 33 critics, indicating "generally favorable reviews". The film has been cited as a favorite by filmmaker John Waters, who presented it as his annual selection for the 2006 Maryland Film Festival.
