Well, it sure does seem as though Patricia MacLachlan often seems to specialise in penning stories about mothers who abandon their children, either by death (as is the case for example with Sarah, Plain and Tall) or by taking off, by deliberately leaving, by going away (as is the case in this here short novel, in MacLachlan’s 1992 Journey).
Basically, in Journey, author Patricia MacLachlan has Liddie (the mother) leave her two children, Cat and Journey (and I really would like to know why Journey is named the way he has been named but we never do get any answers whatsoever regarding this) with her parents and simply, permanently go away. No one knows where she has gone or even why Liddie left in the first place, but her parents (Cat and Journey's grandparents) do obviously fully know that their daughter will not ever return and also tell their two grandchildren (who are now living with them and thus their responsibility) this uncomfortable and much painful truth. And although, periodically, Liddie does send cash for the kids, there are never any letters, never any words of love for Cat and Journey included (which for me also makes those horrid little envelopes of cash rather insulting and almost like a slap in the face, which I think Journey but not so much his older sister Cat painfully realises and must then analyse and work through).
Furthermore, throughout Journey, we as readers are also and actually never told by Patricia MacLachlan how old Cat and Journey are and it is in fact (and for me rather annoyingly so) really hard to make even an educated guess from the textual information provided. For sometimes, in particular Journey acts and behaves really immature and young (like a six or seven year old) but then again he sometimes also behaves and talks akin to an old man as he, as Journey tries to analyse his situation, his memories of the past, and his future, while older sister Cat seems to be like her mother in more than jus her physical appearance, as she very easily and thoughtlessly abandons her flute and the practice of eating meat at the beginning of the story (although none of this is ever textually followed up on, leaving in Patricia MacLachlan's text for Journey and most annoyingly so a huge number of narrative threads that seem to appear quasi out of the blue but then go nowhere and just peter out and mostly vanish so to speak).
And yes, it is precisely the lack of necessary and relevant background information, it is those textual scenarios in Journey that start up but seem to head nowhere (and also the pretty much complete lack of a backstory for basically ALL of the featured characters, and that Cat and Journey's father does not seem to even exist except that we are told he left Liddie just like Liddie later left her children) that leave (in my humble opinion) a storyline so full of frustrating and unsolvable gaps that for me Patricia MacLachlan’s narrative in Journey, it really and truly feels more like a story outline and therefore also an extremely unsatisfactory and thus only two stars tops personal reading experience.