Drayton, a perfectly normal and respectable businessman, is sacked from his job as general Manager of the Dynaflow company after only four weeks in office. The company has been bought out by a Mr. Purvis and the price is suspiciously low. Drayton contacts the I.B. and it doesn't take Smith long to realise that a colossal Purchase Tax swindle is in the making. The trouble is, how to prove it. And that's where Smith has to start playing the waiting game.

The Customs men at a Continental car ferry become suspicious when a man makes too many trips through their port.

Lying to the Customs men - whether about that extra packet of cigarettes or an expensive gold watch - causes more trouble than it's worth. Sheila and Dick Graham find this out when they lie about a valuable microscope found in their luggage, and set McInnes and Smith off on an investigation.

Sir John Dolan and Stuart Campbell are close friends. And we all need friends, don't we?

Ross McInnes learns that a good I.B. man must think of the Department above all things - even above friendship.

When Penman's flat is broken into by a young man, a chain of strange events leads the I.B. into a macabre and dangerous case.

Smith arrests two old clients and oversteps the mark. The two he has accused insist that he himself should be investigated.

Fortunes can be made from a leak of information from a Customs office. Smith and McInnes attack the problem from two sides, both with equal application.

Perhaps to be a good I.B. officer one should have no emotions at all. Ross McInnes finds this out the hard way.

When Paul Valery, an international con-man, has a mysterious visitor, the I.B. become involved with a very undesirable alien.

When Paul Hasek, a foreign diplomat, is caught in a compromising situation, his privileged position is used as a cover for smuggling.

Any way of reducing the price of mink coats would be welcomed by some women, even if it means depriving the country of revenue.

When a man collapses in a Customs hall he is found to be carrying a large quantity of gold.

Smith is involved in butter smuggling between Northern and Southern Ireland and he and McInnes find themselves up against a very professional operator.