This story begins about 3,000 years ago, when Indians made stone tools on what is now the baseball diamond in Mitchell Park at 22nd and S streets NW, and ends last week, with a coverup. In addition to the Indians, the cast of characters includes Early American landed aristocrats, German diplomats and archeologists. The heroes of the piece are a digging dog, an alert advertising executive and a persistent D.C. bureaucrat who invokes a little-known law.

Last month the D.C. Department of Recreation broke ground for a major renovation of Mitchell Park -- a renovation to include a new sculpture garden, a refurbished recreation center and extensive landscaping.

At about the same time, Lynn Hubsch, who runs an advertising agency near Dupont Circle and regularly walks his dog, a black mongrel named Muffin, in the park, noticed that the dog was digging up some unusual rocks. Hubsch, who is a weekend archeologist, recognized them as soapstone flakes -- leftovers from an ancient Indian toolmaking operation.

With a little more digging, Hubsch unearthed a pig's tooth, some pipestems, iron hinges and shards of blue-and-white porcelain. He called an archeologist friend who eventually put him in touch with Geoffrey Gyrisco, an archeologist who works in the historic preservation office of the D.C. Department of Housing and Community Development. Gyrisco got on the phone and found out some federal funds were involved in the park renovation. He was therefore able to invoke a little-known provision of the National Historic Preservation Act of 1966, and order that a survey be conducted to determine whether the project would imperil any historic sites or structures.

"Luckily, the contractor was working [ON repairs to the recreation department house] at the other end of the park, so the project didn't have to be delayed," said Gyrisco, who presided over the dig, which ended last week. "There are really two sites here -- the archaic Indian site and the remains of an 18th-century manor house and farm. Our main concern is that no trees or bushes be planted where they can destroy the remains of the house."

As teen-agers played touch football on the baseball diamond and younger kids climbed on the monkey bars, five archeologists from the Thunderbird Research Company, which won the job under a competitive bidding system, dug test pits and sifted the dirt for artifacts.

Research revealed that the house was built in 1795 by Anthony Holmead, said archeologist Robert Verrey.

Holmead, according to local historians, inherited the land from his uncle, who purchased a 600-acre tract called "Widow's Mite" from the man who received the original land grant from King Charles II. The elder Holmead built a large home called Kalorama, which later gave its name to the neighborhood.The nephew, feeling the pinch of taxes, sold off some of the land. The house he built on the Mitchell Park site was considered more modest than one he built slightly to the west and sold, apparently to the west and sold, apparently to ease financial pressures.

"It looks as if there were a lot of additions built on at different times," said Verrey, who measured the red brick foundation walls and charted their positions on a site map.

The Mitchell Park house apparently changed hands serveral times. By the early 1900s it was in the hands of the government of Germany. When World War I broke out, the U.S. government seized the property. In 1930 the house was razed, and the rubble was plowed under.

"It's tantalizing," said Verrey. "There's so much here -- the Indian artifacts and the 18th-century stuff. We could learn a lot about how these people lived if we had the funds to conduct a real dig. As it is, all we can do is mark and store the artifacts until the District has a place to display them and map the site to make sure no trees are planted where they'll destroy the foundations walls.

"Then we'll cover the whole thing up again. That way, if any archeologists ever want to conduct a real dig, it will all be here waiting for them."