*Marlows and The Traitor" definitely worth getting. I got it from Topsy-Turvey books, who are great! Trying not to do spoilers, but if you don't want any then don't read.
It's focusing on Peter, Nick and Ginty. Ginty I could do without most of the time, but she is better in this book, perhaps because there's no one to show off to. Her main point in this book, from what I can see is to nearly drown, but be able to swim well enough to get out of it.
Peter and Nick make a great pair for an adventure. Peter is the older, and feels he should take the lead, but actually is wracked with doubts about himself.
I think he's a great study in a large family where he's expected to follow in Giles' footsteps and Giles is held up to be a great success. You do wonder sometimes if Giles actually made these mistakes too, but the legends of time (and not having older siblings to remember) has hidden them. I suspect so.
Nick has the confidence of the youngest "no one will really hurt us because we're just little kids", which is challenged a couple of times-like when Foley grabs her.
Between Peter doubting himself and Nick being more confident, it means they can take fairly even measure in the adventure. Even when Peter takes the lead over the escape plan, Nick is able to take the lead with her and Ginty.
Peter has definitely realised that if they get taken on the U-boat then they will be killed, possibly because of his training. I think Ginty doesn't see that far ahead and Nick kind of knows it, but thinks something will happen in an optimistic younger child way.
And the end where Lawrie, having been out of the main adventure with a broken leg, thinks they can't possibly have had as exciting a time as she did, despite her seeing them kidnapped at gunpoint, is an absolute typical Lawrie. I hope Nick enjoyed disabusing her of that, but I suspect Lawrie would still think her adventure was more exciting.