I've mentioned before, I'm sure, that I think Ian MacAlister is one of the great pseudonyms of all time, and it belongs to Marvin H. Albert. What I might not have mentioned is what a dandy book Valley of the Assassins is. It's an old-fashioned adventure novel updated for modern times (1975). The book couldn't be written now because the setting is Iran, Saudi Arabia, and Oman, and the current modern times are very different from those of 1975.
Eric Larson is an adventurer with a boat, and when he rescues the victim of a wreck in the Persian Gulf, he comes into possession of a map that supposedly leads to the great treasure of the Order of the Assassins, a cult that died out long ago. Or did it?
There are a good many others who'd like to get their hands on the map, which comes complete with strange symbols and riddles. Larson puts together a small team to go after the treasure, but the authorities are in pursuit. Still, he and the team manage to slip out of Iran, get to Oman, and cross into Arabia to the Rub-al-Khali, the Empty Quarter, the largest sand desert in the world.
One of the best things about the novel is the settings and the immense amount of detail that Albert uses to describe them. He puts the reader right there in the streets of Basra, in the border country, and in the sands of the Rub-al-Khali. He's also great at the details of the political situation, the way the police operate, and many other things. Reading this stuff is pure fun.
There's treachery and danger aplenty, too, and some nicely described battles in the desert. The problems of desert travel are bad enough without having people trying to kill you. Great stuff, and highly recommended.