Born in Harlan, Iowa, Plummer received a Bachelor of Arts degree from the University of Nebraska–Lincoln in 1937 and a Bachelor of Laws from the University of Nebraska College of Law in 1939.
Plummer worked in private practice of law in Dallas, Texas from 1939 to 1940.
He was an assistant United States attorney of the District of Alaska Territory from 1944 to 1946.
[1] Plummer was nominated by President John F. Kennedy on August 28, 1961, to the United States District Court for the District of Alaska, to a new seat created by 75 Stat.
He assumed senior status due to a certified disability on June 1, 1973.