Mystery book - Starts with an explosion in a museum + floating orb

[xoxogossipgirl]

I read this book in the past year (although the book itself may be older). The first chapter starts off with an explosion in a London or NYC museum (I'm 90% sure it was London) in an exhibition room. There is a floating orb in the begininng that one of the victims sees right before the explosion. And there is a muslim female character who I think was the curator of the special exhibition. I think an American person comes to solve the mystery/crime?

[Ruth]

The Red Pyramid starts with an explosion in the British Museum