Poor physics student Marie (Greer Garson) is studying at the Sorbonne in 1890s Paris. One of the few women studying in her field, Marie encounters skepticism concerning her abilities, but is eventually offered a research placement by Pierre Curie (Walter Pidgeon). They soon fall in love and are married, working together on trying to isolate a radioactive substance Marie has identified as radium. Just as their achievement begins to earn them worldwide renown, Pierre is tragically killed in a street accident. Undaunted, Marie continues to work, going on to make major contributions to science.