Janet really thought that David was kidnapped?

When Janet was accusatory of Brandon, that he had something to do with David not being there I thought it pertained to never inviting him to the party or disinviting him or saying something that would make him not wanting to go.

Did she honestly believe they committed a crime? That they kidnapped him and he was tied up some place? Then why was she not hysterical? Why was she not calling the police? She is angry and disgusted at Brandon but not to that degree.

It was Rupert who suggested she thought that was a possibility which makes no sense. The vibe I always get from Janet toward Brandon is that he likes to manipulate people and said something to David. Not commit a serious felony.