Charlie's car is stolen by Immortal Carl Robinson, an old friend of Duncan's. A former slave, Carl has become disillusioned with the idea of social progress and seems happy to just be a thief.
The episode tries to put a positive spin on Carl's life but it isn't entirely successful. He might not be in danger from lynchings or segregation any more, but he's still a second class citizen. Of course, Duncan's right that things have got better but Carl's bitterness is going to be a hard nut to crack.
Having set up this dynamic, the episode then seemingly gets bored of it and decides to instead introduce a bad guy trying to kill Carl. If this was the first season, he'd be an Immortal and we'd at least get a cool fight in the last act out of it. But the show still doesn't quite know what to do with its new mythology, so instead he's a Watcher, which this week makes him a bad guy. (Did Duncan stopping Horton change anything at all? Where is Joe whenever these guys show up?)
There is at least an attempt to strike a parallel between being racist towards Immortals and being racist towards blacks, and Carl does eventually seem to get a message from it, but it feels worryingly like the episode's ditched a genuine social issue for a fantastic one.
We get a caption giving us the place and date of a flashback for the first time, but only in the first flashback, not the second one from decades later. First of two episodes to feature Carl Robinson, who'll be back in Season 5's Manhunt.