December 16, 1935. Hollywood actress Thelma Todd is found dead in her 1932 Lincoln Phaeton in a garage outside of Los Angeles. Although it seems to be a clear-cut case of carbon monoxide poisoning, some threatening letters sent to people who saw Thelma the day before her death opens the door to a fresh investigation. However, no clear answers would come, and today the actress’ cause of death is still listed as “unknown”.