The Mackintosh Man

Joseph Rearden, a British Intelligence agent, arrives in London and makes a rendezvous with MacKintosh, the head of his organisation, in a discreet office located just off Trafalgar Square. Rearden is shipped off to HM Prison Chelmsford and begins to blend in with the other prisoners. A few weeks later, he is approached by a well-spoken inmate who offers to act as a go-between with an organisation which can spring him from prison in exchange for a large cut of the stolen diamonds. They are used to helping prisoners escape, and have another exit planned shortly, which he can join, if