Extremely Loud & Incredibly Close [suggested by Wendy Gibson]

In a vase in a closet, a couple of years after his father died in 9/11, nine-year-old Oskar discovers a key…
The key belonged to his father, he’s sure of that. But which of New York’s 162 million locks does it open?
So begins a quest that takes Oskar – inventor, letter-writer and amateur detective – across New York’s five boroughs and into the jumbled lives of friends, relatives and complete strangers. He gets heavy boots, he gives himself little bruises and he inches ever nearer to the heart of a family mystery that stretches back fifty years. But will it take him any closer to, or even further from, his lost father?
[product description from Amazon]
The book has a Wikipedia page and has also been made into a film, which has its own Wikipedia page.
Author’s Wikipedia page.
Shortlisted for this month
The book selector for the month can choose up to three books for nomination. This month Wendy’s other choices were:
The Night Manager

In the shadowy recesses of Whitehall and Washington an unholy alliance operates between the intelligence community and the secret arms trade.
Jonathan Pine is ready to stand up and be counted in the fight against this ultimate heart of darkness. His mission takes him from the cliffs of west Cornwall, via northern Quebec and the Caribbean, to the jungles of post-Noriega Panama. His quarry is the worst man in the world. [product description from Amazon]
The book has its own page on the author’s website, as well as a Wikipedia page. It has also been made into a BBC TV series, which has its own Wikipedia page.
Author’s Wikipedia page.
Author’s website.
His Bloody Project

The year is 1869. A brutal triple murder in a remote community in the Scottish Highlands leads to the arrest of a young man by the name of Roderick Macrae. A memoir written by the accused makes it clear that he is guilty, but it falls to the country’s finest legal and psychiatric minds to uncover what drove him to commit such merciless acts of violence. Was he mad? Only the persuasive powers of his advocate stand between Macrae and the gallows.
Graeme Macrae Burnet tells an irresistible and original story about the provisional nature of truth, even when the facts seem clear. His Bloody Project is a mesmerising literary thriller set in an unforgiving landscape where the exercise of power is arbitrary. [product description from Amazon]
The author has a (very sparse) Wikipedia page.