Born in Waipukurau, Hawke's Bay in 1924, Brathwaite was educated at Timaru Boys' High School. He served in the Royal New Zealand Air Force as an air gunner in the Pacific in the latter part of World War II. He married Alison Whyte in 1948 and after a period in the army he began working in advertising.
In 1959, his first book, Fear in the Night, was published. He later became a full-time writer. He wrote over 30 books and numerous radio plays.