"Ambitious", "cold-hearted" and "calculating"; just some of the words used to describe Frauke Petry, leader of Germany's Alternative fur Deutschland (AfD) party. She has suggested German border police should be allowed to use firearms to deter illegal immigrants.

The populist, right-wing AfD has, under her controversial leadership, jumped from winning just a few percent of the vote at the 2013 federal elections, to more than 20 percent in some parts of Germany in last weekend's regional elections. The results surprised many.

But is her brand of politics sincere, or - as some say - pure opportunism? And how far could she take the AfD? Ed Stourton finds out.

Producer: Wesley Stephenson.