Eric Ambler 
Topkapi [PDF ebook] 
The Light of Day

Arthur Simpson is a petty thief who is discovered stealing from a hotel room. His victim, however, turns out to be a criminal in a league well above his own and Simpson is blackmailed into smuggling arms into Turkey for use in a major jewel robbery. The Turkish police, however, discover the arms and he is further 'blackmailed’ by them into spying on the 'gang’ – or rot in a Turkish jail. However, agreeing to help brings even worse danger ….