Born Clarissa Mabel Blank in Allentown, Pennsylvania, she grew up in Philadelphia and graduated from Olney High School with honors. She demonstrated an early talent for writing, beginning her signature Beverly Gray mystery series while still a high school student. Her work was accepted by publisher A. L. Burt and first published in May 1934, when Blank was only eighteen years old.
Blank's Beverly Gray series became her most enduring contribution to juvenile series fiction, spanning twenty-six volumes published between 1934 and 1955. After the initial release, she wrote two volumes the following year and maintained a steady output of one book per year. In 1936, she also published a three-volume series titled The Adventure Girls. Following a publisher transition in 1937, Beverly Gray was acquired by Grosset & Dunlap, allowing the series to continue, while The Adventure Girls was sold to Saalfield Publishing and limited to reprints. In addition to her children's fiction, Blank authored an adult novel, Lover Come Back, in 1940.
Outside of her literary pursuits, Blank worked as a typist and secretary for the Keystone Pipeline Company. She left this position in 1946 to devote her time to her family and her writing. Blank continued to write until the cancellation of the Beverly Gray series in 1955. She passed away from cancer in 1965 at the age of fifty.
