From the minute Reenie Kelly introduces herself to the man on her paper route who will become her pen pal, she's won over the reader as well as touched the heart of a lonely shut-in.

"I've gone door-to-door to say hey to all my customers," Reenie writes to Mr. Marsworth, whose locked gate and "pointy iron fence" only mildly deter the newspaper delivery girl, "and so far I've met all of them but you."

Sheila O'Connor's latest middle-grade novel had me at Page 1. I'm a sucker for unlikely friendship stories, and this one is beautifully rendered through letters between an intrepid 11-year-old and an elderly pacifist.

Reenie and her two brothers are new to town, staying with their grandmother while their father works to pay off the hospital bills that have bankrupted them. Their mother has died and Reenie needs money (thus the paper route), but she also needs a friend (thus her continued correspondence with Mr. Marsworth). But what makes Reenie a most fetching narrator (beyond her letter-writing ability) is her soft spot for underdogs and her loyalty to her brother, Billy, recently 18 and in danger of being drafted to Vietnam.

Through charming letters, Reenie confides to Mr. Marsworth about the town bullies that have targeted her and her brother, Dare. She tells him how they've fought back, how Billy's been working at a gas station, about the letter the Army sent Billy "full of happy, clean-cut soldiers." She tells him about her school pen pal, Skip, in Vietnam and how she worries about him. She asks Mr. Marsworth how well he knew her mother and why the town has ostracized him.

And he writes back, leaving missives in his milk box that explain (in a kind, scholarly voice) his views on war and peace and friendship. He gives her advice about a college that Billy might apply to, and offers Reenie and her brothers use of his abandoned lakeside cottage as a place to relax from bullies and worries about the war.

“Until Tomorrow, Mr. Marsworth,” by Sheila O’Connor

This is sweet story about a girl trying to save her brother from the draft. But it is also a significant historical tale about war, bullies, peace, friendship and family. O'Connor judiciously drops clues, keeping us wondering: What was the relationship between Mr. Marsworth and Reenie's mother? Will Mr. Marsworth ever appear? Why doesn't he use the cottage anymore? What's the story behind the baseball mitt, the blue scooter, the 1950 calendar?

The intrigue comes together in an ending that deftly connects the dots and arouses both sympathy and joy for these very fine characters.

Christine Brunkhorst is a Minneapolis writer and reviewer and a member of the National Book Critics Circle.

Until Tomorrow, Mr. Marsworth
By: Sheila O'Connor.
Publisher: Putnam, 348 pages, $16.99.
Events: 2 p.m. April 7, Wild Rumpus, 2720 W. 43rd St., Mpls., and 3 p.m. April 15, Red Balloon, 891 Grand Av., St. Paul.