Duplicity

 Duplicity is the 5th chapter of Volume three and 21st chapter overall.

Plot
L elaborates by telling Light that his suspicion is only one percent as of now. For Light, that’s still dangerous.

Soichiro Yagami meets with an angry Deputy Director Kitamura who is becoming frustrated with the increasing secrecy surrounding L and the Kira investigation. He is especially mad at the fact that someone came up to his daughter and revealed that he was L. Kitamura asks him if his daughter is a suspect, and Yagami admits this. However, he also sadly notes that the real suspect might be his son, Light.

At a coffee shop, Light tells L that he wants to make sure is completely free of suspicion. L asks him if he could test his reasoning skills. Light is confident that he will not slip up as Kira because he knows exactly what’s been reported on the news and what has not. Then, L shows Light a list of twelve FBI agent who were murdered by Kira, with the order in which they received the file, and the order in which they died. Light sees through this trick and asks L what the exact file they received was. L also hands Light three notes written by prisoners before they were killed by Kira. Light notices that the notes have print numbers printed on the back are purposely out of order, and if he deduces that there’s a hidden message saying “L, do you know gods of death love apples?”, he will be a suspect. Light tells L that there is indeed a hidden message for L in the notes, but rather than saying the phrase that makes the most sense, “L, do you know gods of death love apples?”, if you take into account the printed numbers on the back, it actually says “L, do you know love apples? Gods of death.” However, L tells him that he is incorrect because there’s actually a fourth note, which Light realizes is fake, and the message says, “L do you know love apples? Gods of death have read hands.” L tells Light that he just decided that there were only three notes and didn’t think of the possibility of another one.

L asks Light what he would do if he was L and face-to-face with someone suspected of being Kira. Light answers that he would ask him questions only the real Kira would know. L comments that Light is very intelligent, but that his suspicion of him is now up to three percent. Nevertheless, in order to keep him close and further investigate him, L invites Light to join the Kira investigation. However, Light refuses because he has still not been convinced that Ryuga is truly L.

Suddenly, both L and Light receive a call telling them that Soichiro Yagami has collapsed from a heart attack.

Conception
The title "Duplicity," refers to both sides of the conflict are trying to discover what the other side is really thinking.