The horrifying sex murders committed in southern Ontario by Paul Bernardo and Karla Homolka caught the attention of the media and public of Canada like few, if any, cases in that country's history. Readers of either of the two previous books about the case (Deadly Innocence and Lethal Marriage) may be skeptical that another retelling is necessary, but Invisible Darkness benefits from Stephen Williams's prodigious research and his unique perspective on Karla's culpability. Williams had to jump several legal hurdles unique to Canada's "Crown disclosure" protocols, but eventually was able to gain access to more than 70 hours of videotaped police interviews with Karla, interviews with Paul by his defense attorney, and even psychiatrist's notes. Williams uses vivid vignettes to tell the story, and refrains from unnecessarily graphic details about the crimes. As the Winnipeg Free Press writes, "If any readers still believe [Homolka] was a victim of post-traumatic stress, abused into submission by Bernardo, this will put that idea to rest.