It's been two years since Siberia, and Tony Stark is still dealing with the fallout - personal and political. Life is quite complicated enough, without Bruce falling through a wizards roof yelling that Thanos is coming.
Thor and Loki are stalling, but time is running out. The fate of the universe is at stake. Steve Rogers is back in the picture. Really, the last thing Tony needs is for their plan to go horribly wrong and bring Howard Stark forward in time.
But his Dad *is* standing in his office, whether he likes it or not.
So, it looks like Tony will have to fix that mess too.