A good heroine who is easy to care about makes this short drama watchable, but otherwise it doesn't really work. The plot holes and irrational decisions by the characters are too obvious, and it wouldn't have taken a lot to come up with a much better story based on the same idea. In any movie, classic or modern, a certain amount of implausibility is more than excusable if it leads to a good story, and if the technique is good enough to keep it from being too obvious. But in this case, the lack of logic behind the events is too apparent.
The story starts with a young woman who is "Decoyed" and forced to work for the profit of her abductor. It was one of a number of British movies of the time that were motivated by actual incidents, and the idea could easily lend itself to a movie that would provide both drama and commentary, if the scenario had just been written with a little more care. Too much is unexplained, and while there is plenty of action, too many obvious questions come to mind as you watch it.
One strength of the movie is the heroine, although the name of the actress who played her is unfortunately no longer known. She's attractive, lively, and sympathetic, and while her acting style is just the normal one for this genre and era, it's very easy to care about her, and that makes the movie watchable despite the other flaws.