Just because this info was passed along to me exclusively via a source (at least that's what he said in the email, so who knows for certain if this is really true) does not make it more or less plausible to me, nor should it to you.
If you want to read on about more potential Episode VII plot rumors, proceed ahead. I have paraphrased the info due to some grammatical errors in the source material in an effort to make things flow a little smoother. Otherwise, turn back now...
According to the email I received, the concept of "Luke is missing/needs to be found" in Episode VII is being approached somewhat from the wrong angle in other rumor reports. The source says the "find Luke" premise is based off the cast of young characters (Ridley, Boyega, others?) trying to deal with a problem they uncover that they feel they can overcome themselves, presumably something relating to the machinations of the Sith and/or Empire. They feel confident in their abilities to attack this challenge head-on and quickly realize they are severely out-matched and way out of their league. So they alter their plans and scramble to enlist the aid of Luke, who is unaware of the situation (and how rapidly it escalates to a problem that requires his immediate attention) at the time of his "searching" by the young cast.
The source wasn't sure of Luke's whereabouts at the start of the film or how long it takes for the young cast to "find" him. The source was also unable to ascertain if the above information was part of the original Michael Arndt script or from the revised Abrams/Kasdan script (though I would assume the former).
With the abundance of rumors already swirling around out there, I cannot recall if any portion of what you read above has been provided in a previous rumor report. As always, take this info with as much salt as you desire.
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