After the success of his novel, The Wild Geese (1977) (originally titled The Thin White Line), Carney was asked to write a follow up. At first Carney refused as he just couldn’t come up with a premise for the story, but it was suggested to him the theme could be the rescue of Rudolf Hess from Spandau Prison in West Berlin.
Harvard 1980: a member of a radical human rights activist group, Kathy Lakas, suggests the rescue of Rudolf Hess, then being held for nearly 40 years since the end of the Second World War. Given permission to employ a mercenary soldier to plan the rescue bid, she hires Lebanese mercenary John Haddad.
While on a reconnaissance mission in West Berlin, he is kidnapped by a mysterious group of vicious Germans led by an ill looking middle aged man who torture him and leave him for dead. In hospital, Haddad is visited by British Army Major Reed-Henry who questions him on his activities. Reed-Henry knows the leader as Karl Stroebling, a KGB operative and terrorist group leader.
Haddad travels to Paris and locates an old comrade, Maroun, who agrees to join up with him. Back in West Berlin, he is approached by an American Army Major, Tom Dade. Dade an old friend of the Lakas’ is keen to help and suggests that Haddad seek out Reed-Henry for assistance in rescuing Hess.
The Square Circle was first published in the US in 1982 and, in paperback in the UK (as Wild Geese II) in May, 1985 [Fantastic Fiction].