I'm not quite certain what the point of this book was. Although I was quite happy to return to the world we saw in The Girl with All the Gifts, and was very interested in learning about a different viewpoint during about the same stretch of time, I'm left perplexed about what story Carey wanted to tell with Boy on the Bridge and why. For the majority of Boy on the Bridge, it felt like we were hitting many of the same plot points from Girl with All the Gifts, only with less interesting characters. The dynamics are all the same. We have a gifted child (Stephen Greaves is the new Melanie, except human with severe autism instead of a hungry child), who is very attached to their maternal figure scientists (Samira Khan instead of Ms. Justineau), very aggressive and "we will protect humanity at all costs" military man in McQueen instead of Parks, overt political machinations that are extremely short sighted and do nothing but endanger humanity... it all feels the same. But none of the characters are as interesting or complex as their counterparts in Girl with All the Gifts. I never felt attached to anyone in particular, or cared about understanding where they were coming from. They just made decisions, most of them bad. 
 I felt we also didn't learn anything new about this world. Large swaths of the book try to create tension, but completely fall flat simply because I had read the preceding book. Greaves spends most of his time trying to figure out what exactly the feral hungry children are and if you read the first book, you know. That was the entire point of the first book. I know almost everything I need to know about the 2nd generation hungries and didn't learn anything new in this book about the world. The only things we did learn were details I didn't feel were important. Greaves learns more about how the pathogen affects the brain specifically, how it makes the core temperature cortex of your brain rapidly cool which accounts for the lack of body heat of the hungries, how they gather information through tasting the air, but none of the specifics changed anything. I don't need to know how the pathogen affects the brain to make the hungries do the thing I already knew they could do. 
 Honestly, what frustrates me the most is that there WAS a compelling and interesting story in Boy on the Bridge, it just was shoved way at the back in the epilogue. Without spoiling the events of what occurs in it, the epilogue takes place after the ending of Girl with All the Gifts, and better fleshes out what happens to humanity after Melanie's final decision. The events of the epilogue barely relate at all to anything preceding it in Boy on the Bridge. Some characters are the same but other than that, it doesn't relate at all. I would have much rather had a whole book fleshing out the events of the epilogue, both before it and afterwards, but instead I trudged around with the crew of the Rosalyn Franklin, learned nothing new about the world, and felt primarily indifference when crew members died. 
 Perhaps it is unfair of me to judge the book so harshly in comparison to Girl with All the Gifts. Boy on the Bridge isn't poorly written, and the characters are not bad per say, just not as good as the ones I read before, and too similar to the preceding ones for me not to make comparisons. Perhaps if I had read it before I read Girl with All the Gifts I'd be giving it 4 stars for its inventive world and interesting zombies instead of 3. But that's not what happened and as it stands by itself, it did nothing but fall short in my eyes.