Oh if speculating is all we're doing
that looks very simple:
From the facts available: Trump acquaintance Goldstone contacted the Trump campaign and invited them to a meeting with Russian agent Veselnitskaya. Don Jr said 'I love it' and along with Kushner and Manafort he attended the meeting.
Speculation: That part is the conspiracy to work with foreign agents to affect the outcome of an election, because the purpose of the meeting was to collect opposition dirt on Clinton.
Of course the campaign claims (or claimed, story kept changing) it was to discuss post election policy vis-a-vis orphans and sanctions - something else they shouldn't have been doing as they cannot conduct shadow diplomacy with future promises while not even in office yet; others suspect it was to share stolen emails from the DNC or other opposition research. That part is also speculation: we have to choose which version or versions of the reasons for the meeting we wish to believe.
The next part is also speculation, for which we will have to wait for confirmation in the Mueller report: that Trump himself knew about the meeting and directed his people to attend. There is no reason not to believe that the man at the top had knowledge of the meeting, and the fact that his story also kept changing after the fact strongly suggests a guilty conscience. Trump supporters will scream there's no PROOF
TM (yet) but it defies simple logic to imagine he didn't sign off on it. Still I have to admit, that remains speculation - well-founded speculation, an educated guess, logical based on the evidence, but speculation nonetheless.
That's how I think it went down in a nutshell. Obviously the Mueller investigation is looking at how multiple threads tie it all together but the initial conspiracy apparently centers on that meeting.
