TheforeignspyThomasarrivesinSofia.Inordertogethishandsonsomedocuments,hedecidestousetheyoungmanBoyanashiscover.Theactiontakesplaceatthe"OrientExpress".Ayoungforeigner-drugaddict,thetrainattendantandthesecretaryconductthemission.Thetrainattendantandthedrugaddictarekilled.Boyanisamajorsuspect.However,Thomasisaverynaiveman.TheBulgariancounterintelligencediscoverstheplot.