Who is Anton Haliakov, who has just been abducted by the M.I.5 in London? A Soviet scientist apparently. But sixteen years before the man had another identity, Clément Tibère, and another nationality, French. So what led him to become Russian and to change identity? And why are the British secret services interested in him?

Lino Ventura
as Clément Tibère

Leo Genn
as Chief of M.I.5

Suzanne Flon
as Jeanne

Robert Hardy
as Assistant

Lea Massari
as Maria

Roger Crouzet
as Agent of the D.S.T.

Lucienne Legrand
as Bookseller

Bernard Dhéran
as M.Chat

Pierre Collet
as Mechanic

André Falcon
as Police Commissioner