My first thought when I started reading An Accident of Stars was this: how long is it since I last read a proper portal fantasy book? It used to be quite a commonality, when I look back to my earlier reading days, that magical doohickey that transported someone from our world into another and into the middle of shenanigans.
Anyway, the premise of An Accident of Stars is that it's possible to travel between worlds in a multiverse and one of our main characters, a teenager called Saffron, ends up following someone through a portal to a place called Kena. The woman she follows, Gwen, previously got involved in a spot of king-making in Kena, only to discover that the man she'd helped take over was not what he seemed to be, and now she's on the run from him and his generally nasty ways. Gwen is involved with a ragtag bunch, mostly people who are refugees or in disgrace for one reason or another, and bad things happen to Saffron almost as soon as she steps foot in Kena.
And then it started heading into three stars territory instead of four because of the amounts of info-dumping that happen along the way, which made the plot drag a bit at times. I think in a month where I'd had more impetus to read stuff, I probably would have given up partway through, so maybe the author got lucky with me in terms of timing? Anyway, there's more portal travel, Saffron and her new friend Zech (whose name I had to just go and check, which isn't a great sign) go through a magical ritual and efforts are made to depose the unworthy king. Zech's actions also cause some future problems, as she makes promises she shouldn't have and I fully expect that to come back and bite everyone in the future.
In some ways, the most interesting thing about the book was about Saffron's plans and thoughts on how to deal with returning home. She's been physically mutilated while in Kena, so it's not like she's going to be able to hide that something bad has happened. So, not a bad book but not as gripping as it probably should have been and I can't say I'll be pre-ordering the inevitable next book in the series (A Tyranny of Queens) which will apparently be published in March 2017.