Meet my Hatchet of Death (or, some other colorful description RC Lewis and I come up with at any given moment). This is how I edit myself, it is how I edit others. If you think you want to play with me and my hatchet, shoot us an email.
We all know the first line of a query is your "hook." I call the last line the "sinker." You want it to punch them in the face, in a nice, friendly kind of way that makes them unable to forget you after having read the 300 other queries in their inbox.
If you're looking for query advice, but are slightly intimidated by my claws, blade, or just my rolling googly-eyes, check out the query critique boards over at AgentQueryConnect. This is where I got my start, with advice from people smarter than me. Don't be afraid to ask for help with the most critical first step of your writing journey - the query. My comments appear in green.
It’s been seven years since the world was attacked, five since humanity was forced underground, and approximately one minute since Bem Benson found a reason to do something about it. Love the hook. It's well written and raises questions that are intriguing as opposed to just leading and / or confusing.
Bem is eight years old when the Namante - shape shifting creatures who would be indistinguishable from humans if not for their glowing, silver eyes - attack. I know you're trying to use space wisely but you can bring this description down even further, "Humanoid shape-shifters with luminous eyes" - or something like that. It's not necessarily bad as it stands, just awkward. You don't want to lose them after that great hook. After the resulting war, sheltered Bem is left orphaned and homeless. With only his older, stronger best friend Leo for protection, he joins the other surviving humans in hiding. I think you need to explain why they hide underground. Too weak and clumsy to be of any good, Bem is forbidden to leave the hideout and passes years as housekeeper while the others risk their lives monthly strike "monthly" to gather food and supplies. When a new arrival gains the affection of all, Bem becomes desperate enough to risk an expedition aboveground unclear on why the new arrival would be what makes Bem decide to go aboveground, where a black market of life-saving supplies and information exists despite the Namante takeover. He fails, miserably, and sets off a series of events that bring the Namante to the hideout’s doorsteps. Leo and the others are taken.
Bem sets out with one thing in mind: to find Leo. Things are complicated when he meets Tully, a suspiciously human-like Namante with an agenda of her own which is what? He shares a powerful secret definitely share what the secret is, a query isn't the place to tease in exchange for guidance on his quest and together they fight their way through a war-torn planet to accomplish their goals. Far too late, they realize just how different their goals really are. Forced to choose between protecting the last of his kind this hints that Bem is something other than human. If that's the case, that's a big plot point and needs extrapolated on or saving Leo, Bem has to feign courage to survive in a world where humanity is under attack.
AFTER THE SILVER EYES is a 60,000 word YA/Urban Fantasy. It will appeal to fans of the dynamic characters of DIVERGENT.
Overall this is a well-written query, but you're spending too much time on the backstory. The last paragraph is where your plot actually comes in - an odd friendship, a secret, an alien with an agenda... this sounds like it's actually the meat of your book but you're only hinting at it. Your middle para needs weeded down, your last one needs meated up. Other than that, your hook is superb and it looks like you've got the query-writing skill to get this into good shape.