“I forgive you.”

Are there any three more powerful words? Can “I love you” – also used for countertops, couches, or coats – bestow such mercy? I don’t think so.

“I forgive you.” In release and relief, those words put things back on track – although, in the new book “My Grandmother Asked Me to Tell You She’s Sorry” by Fredrik Backman, the transgressions hardly need absolution.

Every grandmother’s house smells a little different.

Some smell like cookies or old magazines, soup or stale perfume. But seven-year-old Elsa’s granny’s flat – the whole building, in fact – smelled like coffee, cigarettes, a “very large animal of some sort,” and Granny.

For her entire life, Granny was the only friend Elsa had. Granny played games with Elsa, gave her rides in Renault (the car Granny said she won in a poker game), told Elsa stories (Granny loved stories!) and she taught Elsa how to get to the Land-of-Almost-Awake, the magic kingdom of Miamas, and a troubled knight named Wolfheart. Granny had a lot of superpowers, one of which was always being on Elsa’s side.

And that, perhaps, was why she never mentioned the word “cancer” to Elsa. She didn’t want Elsa to know, or to mourn. That was probably why Granny never said goodbye before leaving Elsa with an assignment befitting a knight of Miamas.

The assignment was a treasure hunt (Granny loved treasure hunts!), with clues and messages for people in their building: Britt-Marie, who was a “nag-bag,” and her husband, Kent; the boy who danced, and his mother; Maud, who fixed everything with cookies, and Lennart; Al, who drove Taxi. The first clue took Elsa to the door of a vicious dog that lived downstairs. If the dog didn’t kill her, surely the second delivery would: it was an apology for The Monster, who lived next to the dog.

As Elsa made the deliveries, three more clues appeared until everything – including Granny’s not-so-goodbye – began to make sense. And so did the knowledge that “It’s possible to love your grandmother for years and years without really knowing anything about her.”

Did you ever read a novel that was so captivating that when it was over, you felt a little adrift? That’s how I was when I finished “My Grandmother Asked Me to Tell You She’s Sorry.”

If you can remember that time in your life when magic was real, grown-ups were mysteries, and you were about to learn the truth about both, then you’re halfway to understanding what makes author Fredrik Backman’s book so appealing: though she’s “insanely” precocious, Elsa still relies on a magic-and-pretend life that’s whisked away so quickly, it’s breathtaking. And yet, that having-to-grow-up-fast time is mercifully aborted by the posthumous wishes of the kind of grandmother you’ll wish you had, the one who knows there’s no need to hurry childhood’s exit.

Bring tissues when you start “My Grandmother Asked Me to Tell You She’s Sorry,” but bring your funnybone, too. It’s that kind of book – one that, if you miss it, you’ll never forgive yourself.

The Bookworm is Terri Schlichenmeyer. Email her at bookwormsez@gmail.com.