The Westing Game, by Ellen Raskin
"Uncle Sam" Westing, millionaire paper products mogul, has returned to Westingtown after years away, only to die alone in his bed. Sixteen people, whose families had all recently relocated to the Sunset Towers building, have been selected as Mr. Westing's heirs. But there is a catch: someone has taken Mr. Westing's life, and the heir who discovers the answer will inherit the entire estate. The will designates teams, and each team gets a set of clues.
Each character has his or her own struggles in their lives. They are mourning losses: people, lives that could have been, the chances they missed to meet their true potential. At first the teams seem odd, but by the end of the book, everyone realizes they were partnered with exactly who they needed. I love how the children come the closest to solving the riddle. They also come up with very creative answers with the clues they are given.
Before the game, the heirs barely knew each other, though they lived in the same building. But by playing the Mr. Westing's game, they learned to appreciate the value each person brings to the community. New relationships grow, and new partnerships form.
I think this is a great book for fourth, fifth, and sixth graders. The kids are in the book are very clever, but not necessarily snarky (well, maybe with each other!). The adults they partner with come to value the children's unique way of solving the clues. The reason this book works so well for me is the evolution of the relationships. Husbands and wives fall in love again. A doctor in training learns the effect of compassion. By the end of the book, readers learn that first impressions are not always right, and that relationships can change for the better. A lot of positive things coming out of a murder mystery!