The film opens with a safe-break that yields unexpectedly low gains for the robbers. Daniels plots the bank robbery, having targeted this institution because he has discovered that the main subterranean vault, thought to be impregnable, lies within a short distance of a main sewer. Enlisting the services of a boat-dealer to supply equipment, he targets Booker who, as an architect, has the skill needed to pinpoint the exact location underground. Booker angrily rejects the first approach from Daniels but later, harassed by his bank manager and having to support a new business venture by his wife, he agrees on the undertaking, provided that no violence is to be used. With Gardner keeping watch from a rented nearby office, the titular loophole of the sewer access is utilized by the robbery crew, setting off the bank alarms on entering the vault from beneath and continuing to empty the contents when the police arrive. The police decide the alarms are defective and turn them off for the evening. As the gang are preparing to leave, a heavy downpour of rain starts to flood the sewer system and the gang are seen to struggle against a raging torrent as they are laden with spoils. Booker refuses to leave and remains in the vault hoping the water will go down before the vault is open on business hours. One of the robbers who had been injured by inhaling sewer gas earlier in the scene, Harry, is seen floating away and is presumed to die. The final scenes show Booker in his own studio.
Reception
The staff at Variety said that the core of the plot was one of the few bright spots of the movie. Variety went on to say that the film didn't give Albert Finney and Martin Sheen a chance to show their talents due to the script's quality. The staff also went on to write that the film offered very little in terms of action or suspense. Spinning Image gave the film 5 out of 10 stars with the overall summary of the review being that there wasn't enough peril, that the plot of the heist was too straightforward for most people and that the ending was rushed. Loophole has a 25% rating on Rotten Tomatoes.
