Cheaper than a Gulfstream, nimbler than a superyacht, a second passport—or a third or fourth—has become another trophy for the ultra-wealthy. Even self-styled citizens of the world, it seems, need a Plan B Plus, that gold Maltese coat of arms looks classy. One must keep up. Wealthy buyers “are looking for security”, said Christian Kalin, chairman of Henley & Partners, which provides citizenship advice and publishes rankings such as the Quality of Nationality Index (France is No. 1). They want peace of mind in case of a revolution or other upheaval in their home countries, he said.