The File on Devlin (1969)

A young woman finds herself engulfed in Cold War intrigue when her father a Nobel Prizewinning author vanishes while travelling near the Russian border Entrusted by her father with an unfinished book he was working on before his trip the young woman becomes engaged in a power struggle over the material with her estranged stepmother Suspiciously befriended by a journalist in the midst of the crisis the young woman ultimately learns that no one is to be trusted as her fathers work is of interest to the intelligence departments of several countries