Keep the line open [Cantonese DVD] | Action movie | Heze Cinema HD movies |

Adapted from the Hollywood movie "Cellular", the story tells of a single mother Grace (played by Barbie Hsu) who, on this day as usual, sends her daughter Ruting to school. On the way, they are violently hit by a car driven by the brutal bandit Yihuo (played by Liu Ye). In a semi-conscious and powerless state, she witnesses Yihuo ransacking her house and brutally killing her maid! Then, Grace is kidnapped and locked in a container. Yihuo forces Grace to hand over evidence of his crimes, or he will kill her entire family. In a panic, Grace takes advantage of being unwatched to reassemble a damaged mobile phone and makes a miraculous emergency call, accidentally dialing Ah Bang (played by Louis Koo), an employee in the loan department of a financial company.

Ah Bang's son is going abroad for further studies, and at this moment, his sister Jeanie (played by Maggie Chan) and his son are already waiting for him at the airport, urgently rushing to catch their flight. Feeling half-believing and half-doubting about Grace's rescue call, he casually hands the phone over to traffic patrol officer Sir Hui (played by Nick Cheung). Unfortunately, due to line issues, Sir Hui doesn't hear Grace clearly and warns Ah Bang not to fool around with the police anymore. At this moment, Yihuo suddenly breaks into the container, but fortunately, Grace manages to hide the mobile phone in time. When Ah Bang takes the phone again, he clearly hears a gunshot and realizes the severity of the situation, deciding to save Grace! However, the immediate priority is to prevent the brutal bandit from harming the next target - Grace's daughter. Ah Bang must stop the kidnapper from getting his hands on her daughter. Dangerous events are about to happen, and he may have to risk his precious life to save others...