There are 3 books in the The Crypt Trilogy series. The newest book is Ghost Train which came out in 2016.

1
The Relic of the King

Book cover of The Relic of the King
Buried beneath the streets of London are the answers to an ancient mystery•A wealthy man has secrets he struggles to keep hidden•A hundred people he blackmailed want his painful death•A partner will stop at nothing to keep ancient artifacts his and his alone. Whatever it takes, there will be no…
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2
The Crypt of the Ancients

Book cover of The Crypt of the Ancients
A BUSLOAD OF AMERICAN TOURISTS IS KIDNAPPED AND HELD FOR RANSOM IN GUATEMALA As a sadistic killer holds a group of archaeology buffs hostage deep in the jungle, one of the tourists escapes. Paul Silver came on this trip to learn about the ancient ruins at Piedras Negras, a site…

3
Ghost Train

Book cover of Ghost Train
HAS A NAZI GOLD TRAIN BEEN HIDDEN IN A MOUNTAIN TUNNEL
SINCE WORLD WAR II?

Paul Silver, an international businessman and amateur adventurer, arrives in Berlin looking for information about a fabled Nazi train full of priceless objects and gold. Along with answers he finds a deranged man who hated…