▁than ▁Professor ▁Philip ▁Mort imer ▁he ▁met ▁twenty ▁years ▁ago ▁in ▁India . ▁The ▁two ▁friends ▁summar ize ▁their ▁course ▁before ▁visit ing ▁the ▁factory . ▁At ▁dawn , ▁B enson , ▁Mort imer ▁Bla ke ▁Clar ke ▁and ▁depart ▁for ▁dec ryption ▁center ▁GC ▁& ▁CS ▁at ▁B let ch ley ▁Park . ▁While ▁Mort imer ▁Bla ke ▁un ve ils ▁plans ▁for ▁its ▁revolution ary ▁weapon , ▁the ▁S word fish , ▁a ▁myster ious ▁individual ▁sp ying . ▁In ▁the ▁evening , ▁the ▁two ▁friends ▁are ▁introduced ▁to ▁two ▁desc r amb lers : ▁Z hang ▁H asso , ▁a ▁def ector ▁from ▁the ▁Y ellow ▁Empire ▁and ▁Colonel ▁Ol rik , ▁a ▁special ist ▁in ▁S lav ic ▁languages . ▁Go ing ▁to ▁bed , ▁Mort imer ▁real izes ▁that ▁some ▁sh ots ▁of ▁S word fish ▁were ▁st olen . ▁Meanwhile , ▁Z hang ▁H asso , ▁who ▁expressed ▁no ▁confidence ▁in ▁Bla ke ▁Ol rik ▁at ▁the ▁din er , ▁disco vers ▁that ▁he ▁is ▁a ▁double ▁agent ▁in ▁the ▁pay ▁of ▁yellow . ▁Sur pr ised ▁by ▁the ▁colon el , ▁he ▁man ages ▁to ▁make ▁him ▁believe ▁he ▁also ▁works ▁for ▁the ▁Y ellow ▁Empire . ▁He ▁has ▁no ▁time ▁to ▁warn ▁Bla ke ▁and ▁Mort imer ▁since ▁his ▁last ▁visit ▁the ▁next ▁day ▁mission ▁to ▁Gib ral tar . ▁ ▁Bla ke ▁and ▁Mort imer ▁cast ▁off ▁in ▁the ▁Stra it ▁of ▁Gib ral tar ▁tags ▁designed ▁by ▁the ▁teacher ▁to ▁make ▁it ▁to