The alien offered him the key to the Universe - how long could even a master thief resist?

Rosenberg, Joel, Emile and the Dutchman

To maintain the integrity of their reputation as the galaxy's mercenary elite, the soldiers of the barren world of Metzada adhere to a rigid code of loyalty and honor reminiscent of their Jewish-Israeli ancestors. When a veteran soldier apparently betrays the code, it becomes the ongoing task of his nephew to terminate himif he can. With the same gritty realism found in Emile and the Dutchman, this delivers fact-paced sf action-adventure with a refreshing twist.

Metzada is an inhospitable planet of Epsilon Indi whose inhabitants, most descendants from refugees forced to leave Israel, can survive only because its men are highly skilled mercenaries...Metzada’s one export that brings in revenue. When young Ari Hanavi freezes in combat twice, he has one last chance to survive and even become a "hero". Battle, military command and operations...and a young man who must overcome his terror while dealing with his fellow soldiers and fighting an enemy force in a guerilla war on the planet Neuva Terra, that tests the mettle and the reputation of the galaxy's finest soldiers-for-hire.