In present day (mid-1990s), Tam comes across a homeless woman whom everyone calls Rosey, as in Rosey Rubbish. She is described SO unsympathetically as the most disgusting creature ever. But he doesn't do the sensible thing and stay away from her, instead he ends up... wait for it... going back in time with her! And suddenly it's the 1940s and he's on a farm where he meets a young girl named May, who shares the same dog (like, the exact same dog) as 1990s Rosey. Which is kind of a big, screaming hint that May grows up to be feral old Rosey.
This isn't a time travel book where Tam goes easily back and forth a few times before inevitably getting stuck in the Wrong Time - no, he kind of gets stuck straight away. And time passes at the same speed in both times, so when he finally does get home again he's been missing for three days and everyone is super worried. Thing is, he's kind of blase about going home at times. Like, there are times when he realises that his mother will be worried and he has to get back, then times when he's too busy having fun on the farm. Such a responsible chap. Also, he's not that bright. I mean, he eventually figures out that he's right in the middle of the second world war, but then he finds that his 1990s neighbours lived in the same place in the 40s - back then, a little boy and his mother. And he knows the mother as an old lady, so he goes to her - the 1940s her - and is all, Eveline, it's me, Tam! And understandably she is all WTF go away, you unhinged young man. Like duh, Tam, just because you and the dog can time-travel doesn't mean everyone else can.
Anyway, turns out the 1940s farm was destroyed in a fire and the lovely old farmer died, and the young girl (a war orphan already) went crazy and was put into a home. So Tam gets the idea that he can go back and warn them, but then old Mrs. Pickles - the cook/housekeeper in the 1940s with whom he meets up in her 1990s nursing home - tells him that he can't change the past, that what's happened, happened. But he still wants to go back and warn them, but then one night he sees Rosey/old!May and the dog, and the dog has singed fur, and he realises that the fire has already happened. Oops. But he goes back in time anyway to... I don't know. I have no idea what his plan was here. But at least he FINALLY realises that Rosey is May grown up - after, of course, being disgusted at the idea and yelling at her that May is dead. Charming boy!
So then the book ends with him back in the 1990s, telling his mother (at 5am, after having banged around the kitchen so much that she woke up) that the homeless lady is going to live with them now, and that her name is May, and naturally his mother is horrified because she's in their clean kitchen, using the best china, and looks/smells like she hasn't had a bath in fifty years. And that seriously is where it ends, with Tam snapping that her name is May, not Rosey. And like, he's about 12 or so and was friends with this 8-year-old who is now in her 50s or so... how, EXACTLY, is this going to work?!
I was hovering between two and three stars for this but in the end, I don't think I liked it quite enough to give it three. The village- and farm-life in the 1940s was interesting to read about, but I just couldn't bring myself to like/care about May, young or old. Sorry.