In the beginning of Sherlock Holmes (2009), Lord Blackwood attempts to kill a young woman during some sort of dark ritual and is thwarted just in time by Holmes and Watson. Blackwood himself was not going to do it, instead he put her in some sort of "spell", causing the girl to attempt to stab herself.
Given that the "supernatural powers" of Lord Blackwood were revealed as nothing more than "conjuring tricks", why did the girl try to stab herself at the direction of Blackwood?