JOHANNESBURG—It is springtime dawn in Equestria, a far-eastern suburb of Pretoria, South Africa’s capital. A heatwave’s scalding the area, with a temperature well over 80F—even though it’s only 5.30 a.m. It is weather more characteristic of midsummer. 
And things are about to get hotter. 
A 20-strong group of men and women in plain clothes, some with pistols and assault rifles ready, descends on a townhouse that looks like every other one in the complex; neat, with a manicured lawn and small garden, a fountain gushing water into a pond containing a few orange and black koi fish. …