There is a very nasty one going on in Canada now, mostly Toronto and Vancouver area. They target Chinese nationals studying in Canada, people who have a limited knowledge of how things work and perhaps a distrust or fear of authority. They call a student in Canada and then a parent of a student back in China claiming the student has been kidnapped and to send money to [some account] for a ransom.
They call the student and suggest some bogus "investigation" and to not answer their phone unless from the "investigator's #" and warn any text or eMail may be faked. So the student basically cuts themselves off from their parents.
The parents, meanwhile, are told to pay a ransom, and not being able to contact their child, panic and pay out.
Note that due to the unique names of Chinese students, and the fact that anyone that can afford to send their child to study in Canada is obviously of some means, it's quite profitable. The success rate is low, but it's greater than zero.