The Tunnel

Based on an incredible true story, THE TUNNEL tells the story of Harry Melchior, a champion East German swimmer at odds with the Communist system under which he had already been imprisoned. After his release from prison, he promises to remain in East Germany but manages to escape just as the Berlin Wall is being completed. While he successfully fled the oppressive Communist regime, his sister and her family were not able to escape. Harry is determined to rescue his sister and her family, and with his best friend, Matthis Hiller, an engineering genius, the idea of the tunnel is born, but the project does not run smoothly.
Despite renting out an abandoned building right next to the Wall with no questions asked, the participants struggle with the massive logistics of their task. Quickly realizing that it would take years to complete the task alone, they enlist helpers, each with their own family or friends that they wish to rescue as well. With the additional helpers comes the risk that any of them could be a traitor.
An interesting side note is the truth of the NBC television network's involvement in the process. The network had planned a fictional story about tunneling through the wall, then scrapped their own plans and filmed the real heroes as they completed their nine-month long mission.
The pace of the film is always brisk as the threat of the tunnel collapsing always weighs heavy on the protagonists' minds, the worries that their tunnel could open in the wrong place, and the very real threat of the East German police discovering the plot.