The major mystery of Disclaimer revolves around uncovering the truth about what happened to Catherine, Nicholas, and Jonathan in Spain in 1993. Renée Knight shows how several characters, in their quest for the truth, subconsciously instead seek confirmation of their existing beliefs. Nancy, Stephen, and Robert are the main characters who warp evidence to fit a narrative they’ve already constructed. These characters stubbornly refuse to hear other versions of events, which draws them deeper into their own biases. 

Nancy believes her son’s last act was an act of heroism, so she seeks out Catherine to understand why Jonathan would sacrifice himself for a boy he didn’t know. Catherine doesn’t want to burden Nancy with the crime her son committed, but Nancy reads Catherine’s silence as cruelty. Nancy believes Catherine is guilty of something, and the evidence she finds in Jonathan’s photos further confirms to her that Catherine is to blame for Jonathan’s death. Because she believes in Jonathan’s innocence, Nancy constructs a narrative of Jonathan’s last moments in which she paints Jonathan as a victim and Catherine as a promiscuous, uncaring mother who deliberately sought to manipulate him.

Using what Nancy imagined occurred between each of Jonathan’s photos, Stephen—holding unwavering faith in his wife and unwavering anger at Catherine—decides that even the more far-fetched elements ultimately work to “[release] the truth” (251) even if they do not conform to facts.