Two young Israeli agents, narrator Josef Ascher and his sometime lover Hanita, are undercover in Belgrade. Their mission is to find and kill PLO super-terrorist Razak--who will soon arrive in town to plan his mission: the violent hijacking of a train of Soviet Jews, bound for Israel, as soon as the train crosses over the border from Czechoslavakia to Austria. (The USSR, supposedly relaxing its emigration policy, is actually conniving with the PLO in this scheme.) And there's intense interest, from everyone, on one emigrating Jew in particular: dissident scientist Yitzhak Abramov, a symbol of Soviet Jewry. . . and the one man who knows the identity of Israel's ""mole"" in Moscow. Thus, with help from Milan Buric, an old local (who was a Yugoslav WW II partisan along with Josef's father), Josef and Hanita are determined to eliminate Razak before he can go into terrorist action. But then Josef gets thoroughly distracted--he catches sight of a Nazi villain, long presumed dead!--and, as a result, Razak eludes them. Worse yet, old Buric is murdered. The Belgrade mission is a failure. So, while trying to figure out how that long-ago Nazi is involved in all this, Josef escapes to Athens and comes up with an alternate plan: he and Hanita will go to Russia, take the place of two Jewish emigrants on that train, and be ready to fend off the Razak hijacking when it occurs. (Their orders from Israel: if Abramov can't be protected from capture by Razak, the scientist should be killed.) And eventually Josef will try to save the train from Razak by hijacking it himself--a ruse which doesn't completely succeed: there's a final battle/confrontation with the PLO terrorist. . . followed (back in Israel) by a rather longwinded explanation of the whole operation's real purposes, including the role of that Nazi villain. A few too many tangles, a few too many contrivances--but first-novelist Karlin delivers this somber action/espionage in plain, leanly atmospheric prose; and, with the moral tensions rarely belabored (Josef kills frequently, questions his orders, yet never whines), this is an above-average spy parable, evocative in its backgrounds and quietly effective in the Israeli-agent characterizations.