Guendolen Carkeek Plestcheeff was born in Seattle in 1892 at the First Hill mansion home of her parents, British-born Morgan and Emily Carkeek.

Born in Redruth, England, Morgan J. Carkeek emigrated to the United States in 1866. Carkeek married Emily Gaskill, also from England, in 1877, and the couple settled in Seattle in 1885. Morgan Carkeek was an accomplished stonemason and successful building contractor who built several of Seattle's early stone buildings, such as the Dexter Horton Bank, and large office buildings, including the Burke and Haller buildings. Carkeek built the family mansion in 1884 on Seattle's First Hill, at the southeast corner of Madison and Boren Streets, at the time one of Seattle's most fashionable neighborhoods. Emily Carkeek hosted many society events at the mansion, where she also founded the Seattle Historical Society on November 13, 1911 with the first “Founders' Day” ball, with guests dressed in historic costumes related to early Seattle. The party became an annual, invitation-only event, to which guests were asked to bring artifacts or documents related to Seattle history. In 1918, Morgan Carkeek donated land for a city park on Pontiac Bay on Lake Washington at Sand Point, designating a portion of the property for a museum to house the growing Seattle Historical Society collection. Such a building was never realized and the park was displaced in 1926 by the Sand Point Naval Air Station. Morgan Carkeek donated his compensation payment back to the City toward the purchase of land in Piper's Canyon for a new park, the present day Carkeek Park.

Guendolen was the second of two Carkeek children. Her older brother Vivian, born in 1879, was a graduate of the first University of Washington Law School class in 1901 and practiced law in Seattle. Guendolen attended elementary school at the old Pacific School in Seattle, and at age 13 was sent to Europe, first to a French school in England, and afterward to finishing school in Lausanne, Switzerland. Shortly after the teenaged Guendolen's return from Europe, she met dashing young Italian diplomat Paulo Brenna, who was serving as the Italian consul in Seattle. In 1921, young Guendolen and Brenna married in London, then moved to France where Brenna served on an international body for postwar reconstruction. She and Brenna took full advantage of all that Paris had to offer--theater, opera, museums, parties-- sometimes attending several events in one evening. Guendolen fell in love with the city, a second home which she would return to again and again throughout her life.

Shortly afterward, Brenna was named Italian minister to the new Republic of Estonia. After a brief stay in Brenna's hometown of Rome, the couple moved to Reval (now Tallinn), the Estonian capital. During this period, Estonia was home to many refugee Russian aristocrats escaping Bolshevism. Among them was a tall young man from Moscow named Theodor Plestcheeff who had, after several failed attempts, succeeded in escaping across the border using the identification papers of a sympathetic Russian policeman. Plestcheeff was from an aristocratic family related to the noble Stroganov family on his mother's side, and had once served in the court of Czar Nicholas II. Guendolen met Plestsheeff through mutual friends, and discovered that they shared many interests and tastes. Plestcheeff knew a great deal about Russian art and antiquities and introduced Guendolen to the world of Russian arts and crafts, particularly Russian porcelains, which she began to collect.

Guendolen's marriage to Brenna ended in 1928. Rather than returning to Seattle as her family wished, Guendolen moved to Paris, meeting Theodor Plestcheeff there; the couple married in 1929. The Plestcheeffs traveled back and forth between Seattle and Paris for a few years, settling in Seattle after Morgan Carkeek's death in 1931 and moving into the family mansion on Boren Street. In 1934, with the neighborhood no longer as fashionable as it once was, Guendolen decided to sell her parents' home, to be demolished and replaced with a Standard Oil service station. Not one to let such an event pass quietly, Guendolen commemorated the mansion's demise with an exclusive society event held on the premises. Guendolen decorated the house in 1890s style, guided by 1896 Christmas family photograph, and guests dressed in the fashion of the 1890s, the women in bustles and prim necklines, and the men in top hats and fake walrus moustaches. This "Gay Nineties" farewell party, according to local newspapers, was the social event of the season.

In 1937, the Plestcheeffs bought the five-story 1909 stone mansion on East Highland Drive that was built by eccentric Seattle capitalist and "Good Roads" advocate Sam Hill. The house had fallen into disrepair since Hill's death and Guendolen took charge of its renovation: she had the windows enlarged, installed a skylight and redesigned the rooms, decorating them with her own collection of European antiques. The Plestcheeffs also later bought and rejuvenated a waterfront cottage on Bainbridge Island as a summer home, placing the original iron gates from the Carkeek mansion at the entrance to the property.

Following in her mother's footsteps, in 1938 Guendolen became president of the Seattle Historical Society, a position she held for 17 years. She began to raise money for a new home for the Society's historical artifacts, originally collected by her mother Emily, and stored in the Plestcheeff's basement. After years of fundraising and political wranglings, the Seattle Historical Society acquired property off Lake Washington Boulevard, where the Museum of History & Industry opened in 1952.

Though Theodor Plestcheef died in 1967, his influence on Guendolen survived in her wish to share her enthusiasm for the decorative arts, and in tangible form in her extensive collection of Russian decorative ware. In 1987, Guendolen established the Plestcheeff Institute for Decorative Arts, a non-profit center for research and education in the decorative arts, to be housed in the Sam Hill house, which was still her home. Plestcheeff willed the house and its contents to the University of Washington, after plans to donate the building to the Seattle Art Museum fell through. She lived in the mansion until her death in 1994 at the age of 101, and the building continued to serve as the Plestcheeff Institute for Decorative Arts for a few years afterward.