Waterguard Training School trains young men to become officers of the anti-smuggling branch of H.M. Customs.
C/U of suitcase on a table, tilt up to a Customs Guard holding declaration form. M/S of a man and the guard, the man places a bottle of wine and a tennis racket next to his case, he opens his case and takes out a bottle of gin and some cigarettes. C/U of the guard, tilt down to show him rummaging in the case, once satisfied he marks it with chalk. A more senior guard enters and stops the man repacking. The senior guard carefully unpacks the case - an illegal flick knife is found in a shoe and smuggled watches in a false sole.
M/S of the senior guard teaching trainee customs officials. C/U of the senior guard opening a book revealing more smuggled watches in a secret compartment. The senior shows the class a tennis racket. C/U of a trainee. The senior guard opens the handle revealing diamonds, he passes it down a row of students. C/U of a suitcase with a false bottom for storing drugs. C/U of glass bottles containing drug samples - cannabis, heroine, amphetamines etc. The senior guard opens the cannabis jar and sniffs it, he passes it to the trainees - they must learn to recognise the smell! C/U of the senior and the student examining an opium pipe. C/U of a trainee sniffing a bundle of hemp and examining a small pipe.
M/S of a senior guard and students looking at a model ship - they learn from the model secret hiding places used by smugglers - in pipes, coal bunkers etc. A trainee carefully lifts potatoes from a pot - he discovers one has a diamond broach concealed inside a secret compartment.