The series features four men who first met whilst fighting in Italy during World War II. The men later reassemble and decide to fight for justice and against tyranny, using money set aside for the purpose by their late commanding officer.
The series is unusual in that the four lead actors appear in turn, rather than together, and are never seen together other than in the first episode.
The series was loosely based on a novel by Edgar Wallace.
* Richard Conte as Jeff Ryder, a lawyer in New York
* Dan Dailey as Tim Collier, an American journalist based in Paris
* Jack Hawkins as Ben Manfred, a British MP who works from London
* Vittorio de Sica as Ricco Poccari, an Italian hotellier based in Rome
Each character had an assistant who was only seen in the episodes they starred in:
* June Thorburn played Vicky, Jeff Ryder's girlfriend
* Honor Blackman played Nichole, Tim Collier's secretary
* Andrew Keir played Jock, Ben Manfred's best friend
* Lisa Gastoni played Giulia, Ricco Poccari's girlfriend
* Guest stars included Judi Dench, Alan Bates, Leonard Sachs, Frank Thornton, Patrick Troughton, Donald Pleasence and Doctor Who villain Roger Delgado.