American pharmaceutical executive Walter Richmond takes a business trip to Amsterdam, accompanied by his wife Cathryn and their 10-year-old daughter Melissa, who has been mute ever since an accident some time ago. To communicate, Melissa uses a small magic marker board that she wears around her neck. Melissa makes a trip to the ladies' room at the hotel De L'Europe and gets separated from her parents. Melissa wanders out of the hotel and onto the street, where she witnesses the murder of Simon Van Der Molen, the attorney representing Walter's Dutch client. Unfortunately, Melissa is spotted by the killers, who are hit man Bruno Decker and his employer Rudolph Hartman, who turns out to be Walter's client. Hartman had Van Der Molen killed to prevent Van Der Molen from revealing the side effects of Hartman's new medication, which he's marketing to Walter's firm. If Van Der Molen would have told Walter about the side effects, Walter would have declined the medication, and Hartman would have been out of a chance to make a lot of money. Melissa finds temporary refuge with a homeless man named Simon, then eludes Hartman by stealing a police car, which she immediately smashes into a bistro, because, of course, she doesn't know how to drive. Melissa is reunited with her parents at the hotel, but Walter innocently reveals to Hartman Melissa's recent adventures and whereabouts. Hartman tells Decker where Melissa is, and Decker pursues her from her room, down an elevator shaft, and into the suite of rock star Billy Boy Manson, who tries to sexually assault Melissa. But Decker arrives and kills Manson for getting in the way. Having escaped Manson's clutches, Melissa eludes Decker by climbing out onto a ledge and plunging into the canal below. But Melissa isn't even safe in an ambulance: after Decker is killed, Hartman carjacks the ambulance and drives off. Can Walter and the police stop Hartman from killing Melissa before she reveals that it was Hartman and Decker who killed Van Der Molen?