Roger Moore and Ray Milland star in this 1970s action drama. Rod Slater (Moore) becomes involved in a web of intrigue following a rock fall at a South African gold mine owned by Harry Hirschfeld (Milland), in which general manager and veteran miner Frank Lemmer (Norman Coombes) is killed. Hirschfield's managing director, Manfred Steyner (Bradford Dillman), is plotting with financier Farrell (John Gielgud) to flood the Big Dyke, thus destroying the mine and raising the value of gold worldwide, and tricks Slater into excavating the seam of gold beyond the river. Meanwhile, Slater becomes passionately involved with Steyner's wife (Susannah York), unaware that the scheme hatched by her husband will result in his death.