Given the question: Who threatens to call the police?  Answer the above question based on the context below:  Generally, the film is a dark and quirky "tragicomedy". The "everyman" protagonist, Dr. Frank Sangster, is a dentist with a fairly pleasant but rather innocuous, ordinary and uneventful life. But all of this gets derailed, and Frank's life descends into an increasingly complex mess, from the minute a beautiful and seductive new patient named Susan Ivey comes to him, seeking a root canal and a little pain relief. On Susan's initial office visit, Frank schedules her for a root canal the very next day, and offers her some Ibuprofen to address her pain in the meanwhile. Claiming that she is allergic to the offered medication, Susan requests a prescription for the addictive pain-killer Demerol. Frank provides the prescription, but only for five tablets. However, Susan changes the dosage from five tablets to fifty when she collects the medication from her pharmacist. Susan arrives for her appointment twelve hours late, having mistaken the time. She seduces Frank, talking him into getting drunk and having sex with her. During the night, Susan steals all of Frank's narcotics. The next day, there is a DEA agent at Frank's office demanding to see the dentist's narcotics supply, because an 18-year-old has driven a car off a cliff under the influence of cocaine hydrochloride from a bottle registered to the dentist. Knowing that Susan has stolen his entire drug supply, Frank puts the agent off, saying he dispensed it all to patients. The agent leaves with the promise that if Frank fails to produce the empty containers in two days, the DEA will place him under arrest. That night Frank goes to Susan's hotel room to demand the empty containers, threatening that he'll call the police if she doesn't provide them. Once again, she overrides his initial intentions and seduces him - with the result that they have sex and he spends the night with her.
The answer is:
Frank