In this week's episode of Intruders we get a bit of explanation, a bit of backstory and a bit of violence by a couple of characters. But the mystery of John Simm's accent remains unresolved. Spoilers ahead.
After an odd encounter while returning his neighbors' car (could the wife be any more suspicious?), Jack goes home and hears Amy's explanation for her disappearance. It certainly sounds reasonable (how many phone numbers do you know off the top of your head?) but since Jack is already suspicious he's not sold. Especially when combined with Amy's abrupt changes in behavior. Jack is losing it as he sees the love of his live seeming to change into another person. So Jack is understandably angry and confused.
We see the incident that led to Jack leaving the LAPD. He was lying in wait for three men who he gunned down. Of course there's more to the story since Jack's not in prison for murder*.
Meanwhile, Richard Shepherd is having his own flashback. He meets the previous incarnation of Marcus, who is on the run from the Nine. Marcus makes a deal with Shepherd to let Marcus go for now and later bring him back in exchange for cash. The sand dollar is presumably a memory trigger, like the yellow 45 record adapter in the first episode**.
Shepherd isn't the only one on the road to Seattle. Madison is riding with the woman she paid to take her. Madison tells a story about Mozart. The highlights of that story are the mentions of a serial child killer and Marcus being in the orchestra. Combine those tidbits with the drowning of the cat and and you can make a guess what sort of person Marcus is.
Unfortunately for the woman, she's starting to have second thoughts about the little girl with lots of cash. She snags the 9 card from Madison. Since her cell phone is dead she pulls in at a rest stop to use the pay phone. Of course it's Shepherd's cell number so now he has a lead. Madison snatches the phone from the woman and smashes it. She switches to innocent child mode and lures the woman into the rest room.
When Shepherd arrives at the rest stop he finds an empty vehicle and the woman's dead body in the rest room. Shepherd does the cleaner bit - burn the vehicle and the body (after removing the teeth). It's possible that the woman slipped, struck her head on a sink, and stumbled around bleeding before collapsing in the stall as Madison watched in horror. But I don't think that's what happened. Don't pick up precocious ten year olds with a lot of cash. It never ends well.
It looks like next week all roads lead to Seattle.
*I don't know if the show is going with the book's explanation but since the miscarriage was mentioned I'm guessing yes.
**The memory triggers are mentioned in the book. They're simple but uncommon objects that one isn't likely to encounter by accident.