In October alone -- a month traditionally among retailing's slowest -- National Theme Productions Inc. (NTP), an eight-year-old specialty clothier based in San Diego, expects to gross more than $18 million. Add in 11 more months of similar receipts, and you'd seem to have quite an enterprise in the making.

But unfortunately for owners Paul Thomas and Paul Sullivan -- and most of NTP's employees -- theirs is not business as usual. Designing and marketing sophisticated Halloween costumes (ranging from a one-piece Rabbit-in-a-Hat to a scanty French Maid outfit), 90% of them for yuppie-income grown-ups, NTP has niched itself into a spooky corner.

Each fall, the basically 20-person company gets pumped up like a Thanksgiving parade balloon. First NTP trains several dozen area sales managers, who in turn hire and train about 180 regional managers, who sign on counter clerks, who sell the stuff that NTP sews. In all, no fewer than 6,000 employees will pass through its payroll this year, operating some 900 retail outlets nationwide. Each outlet is actually a full-service concession housed for the month within a larger retailer -- such as Sears Roebuck and J. C. Penney -- in whose name the merchandise is labeled. The host enjoys a guaranteed skim off the top and the guest neatly vacates the premises come November, at which point the 6,000 hirelings stream back onto the street.

"That's the tragic thing about our business," grants Norman McKinnon, NTP vice-president of marketing. "We train the managers to become capable of running a retail operation. They learn how to hire and fire, to discipline employees, to handle cash and inventory, to display and to sell. We put them into business and let them work for us for 30 days, and then they go away."

For the most part, NTP's massive recruiting effort is wasted like so much candy corn. As expert at training as it is at merchandising, the company is searching for additional themes, but other hot niches -- Christmas, Easter, Mother's Day -- are already staked out.

One thing they might try: training the force to dispose of overstock. In NTP's warehouses, for example, are hundreds of Darth Vader disguises left over from 1983, not to mention several thousand long-haired Boy Georges that were superannuated on the day Boy trimmed his braids. Otherwise, the vexed company welcomes suggestions.