The Lost Symbol by Dan Brown (2009) Doubleday

Another in the series of Professor Langdon’s thrillers related to symbology.  In this episode, Langdon is invited to a presentation by one of his former students at the Bilbao museum in Spain.  But before the man can do the final reveal, he is killed by a sniper.  Langdon and the host museum’s leader, who is also the fiancé of the Spanish prince, pursue releasing the information anyway, which the assassin was sent to prevent, so he turns his eye on Langdon and pursues him into a cathedral.