The Spear of Destiny is an action/adventure novel. The sequel to 'Tomb of the Lost'
These books need to be read in order.

Three months after their failed expedition to recover the sarcophagus of Alexander the Great, marine archaeologist Natalie Feltham and journalist Peter Dennis are at the British museum for the premiere of the Holy lance of Longinus, the fabled 'Spear of Destiny' exhibition.
When the spear, believed to contain magical, mystical healing powers for its bearer, is stolen at gunpoint Peter and Natalie are asked by Interpol to help catch those responsible, believed to be led by the German Count Otto Brest Von Werner.
Once again Natalie and Peter are plunged into a world of adventure and destruction as their quest takes them from London to the streets of Rome and onto Palestine and the supposed final resting place of Jesus Christ.