Francis Crick is associated with two discoveries, probably two of the most important in the 20th century: the double helix of DNA and the genetic code. The first he discovered with James Watson; the second he worked out mostly by himself, though with contributions from many others.

Despite Crick’s extraordinary distinction as a scientist, little has been written about his life aside from his brief autobiographical essay, “What Mad Pursuit,” and his leading role in “The Eighth Day of Creation,” Horace Freeland Judson’s outstanding oral history of molecular biology.

The first biography of Crick, who died in 2004 at the age of 88, has now appeared. Called “Francis Crick, Discoverer of the Genetic Code,” it is by Matt Ridley, one of the few journalists Crick was in the habit of talking with. Mr. Ridley has created a vivid portrait that explains Crick’s scientific work with clarity, deftly outlines his career and provides sharp insights into the nature of Crick’s remarkable creativity.

Crick, who set a high value on his privacy, seems not to have left biographers a great deal to work with beyond what is already on the record.