OOTS #1217 - The Discussion Thread

[Petrocorus]

I'd say when Vader realized they were after Leia. Nothing beforehand really stretched imagination, especially since they had a Jedi with them most of that time.

This.
Once Vader understand the Falcon's crew want Leia, he has everything to form his plan. He doesn't need to know anything about the crew, he's already sure Leia is with the Resistance, so he can assume they are or close enough.
Not to mention he does sense Obi-Wan through the Force at some point. A bit later i think.

The second biggest problem is that Leia realizes they were let go, and then leads them directly to the rebel base anyway. Why didn't they stop somewhere and get rid of the tracking device, or drop off R2 and deliver the plans without using the Falcon, or stop and make hundreds of copies of the plans and send them all to the rebels by different routes and agents, or post them on the galactic internet where anyone could download them?

This is the one things that has always bugged me about it. That may be explained in a cut scene (the movie was heavily edited) but Leia indeed has every reason not to go straight to Yavin.

Vader says "her resistance to the mind probe is considerable. It will be some time before we can extract any information from her."
So Vader felt it didn't fail, he just needed more time. Then Tarkin tries his method and does gets a lie, and then in a fit of pique decides to "terminate her. Immediatly" which apparently doesn't mean "right now" because she's still waiting in her cell when Luke arrives.
Since Tarkin was willing to throw Leia away completely after one atrrempt at getting the location from her it doesn't seem like finding the rebel base really is his highest priority.

Or more that he was sure she'd never break and give them anything useful.