Legends Untold by Sophie Davis
I need the next one right now.
Couple quibbles: They go back to the time of Lady Jane Grey, London 1500-whatever. Language used by the contemporaries isn't really true to the time, but not too jarring to someone not expecting historical accuracy, except a few times. Once, when Lady Jane says, "okay". Um, yeah, that's so anachronistic it's jarring. Another time another contemporary says it, and our MC says it to a contemporary - when she's a time traveler trying to, you know, fit in with the time.
In one scene Lady Jane is wearing silk pajamas. I'm not an expert but I'm pretty darn sure women didn't wear pajamas in the 1500's. Pants of any sort were a big NO, even for sleeping attire.
But with the story it's really pretty minor. I don't expect anyone reading this, particularly after reading the first two and knowing what to expect, is going to be displeased. A thoroughly enjoyable time travel adventure. Sadly ending, again, in a cliff-hanger.
I NEED the next one!