I've read most of MCS' more recent books (Dec. 6th and Wolves Eat Dogs are still on the TBR, though!), so I was intrigued by this earlier (1972) novel, published before he achieved success with ‘Gorky Park.'
The book shows the author's ongoing interest in creating protagonists from a variety of ethnic and social backgrounds – here, art dealer Roman Grey, although he lives in NYC, is a Romany Gypsy.
The story is a fairly basic action/mystery – the holy Crown of St. Stephen (http://en.wikipedia.org/wiki/Holy_Crown), a potent political and religious symbol to Hungarians, is due to be displayed at St. Patrick's Cathedral in NYC, before returning to Hungary. But various groups may be out to steal the relic for their own purposes. And is the crown even the original – or a clever fake? Roman Grey has a trip with his girlfriend planned – but gets blackmailed into using his expertise to analyze and protect the Crown. Of course this all ends up in a dramatic and action-packed shootout.
Not bad, for a quick adventure – but not up to the standard of MCS's later work, either.