Time travel is not easy in the world of Outlander. In the eighth book, Roger and Buck MacKenzie head through the stones to get to Jemmy. Only, they don’t end up in 1778 like they think they will. They end up in 1739.
On top of that, Jemmy isn’t even in the past. He’s in 1980 and Bree is the one to save him from Rob Cameron. So, Roger and Buck end up in the past, in a time they don’t expect, and for a very different reason.
Why do they end up 40 years earlier than they’re supposed to be? It’s all linked to another member of their family.
Roger and Buck end up in the same time as Jeremiah MacKenzie in Written in My Own Heart’s Blood
The two were certainly thinking of Jeremiah MacKenzie, but it’s a different Jeremiah the magic of the stones take them to. Roger has something important to do for his own family.
It turns out that Roger’s father, Jeremiah MacKenzie, time traveled during the Second World War. Rather than being lost at sea, he ends up in 1739. Roger needs to get to Jeremiah to make sure he can get back to his own time to be able to save Roger in the fall from the stairs as the tube tunnels collapse during the Blitz.
This is why the stones take Roger and Buck to 1739. If Roger didn’t save his dad, Roger wouldn’t be alive now. We know by Roger still being around that time worked as it was supposed to.
What about Buck? That’s hard to say since he was thinking of young Jemmy. However, we know that time travel isn’t an exact science. Roger spent some time trying to figure it out to help his children, but in the end, it’s clear that sometimes the magic of time travel has its own needs. Otherwise, why would Claire end up in 1743 when she had nobody to think about to anchor her to there?