Oliver "Boo" Dalrymple is dead, and surprised to find himself in Heaven at age 13.

It's not exactly what he expected: segregated by age and community, Heaven exists as fragmented townships that operate to their own peculiar rules. As our hero slowly acclimatises to his new afterlife, he is joined by a friend who reveals that Boo was not felled by his weak and "holey" heart, but was shot by a classmate who went on a rampage with a gun at their high school. Is "Gunboy" also in Heaven? Boo and Johnny determine to uncover the truth, but the answers they find are more troubling than they could ever have expected.

Boo, Neil Smith's first full-length novel following his acclaimed short story collection Bang Crunch, is an odd mix of Alice Sebold's The Lovely Bones and Mark Haddon's The Curious Incident Of The Dog In The Night-time, perhaps edging a little too closely to the latter on occasion. Boo is at once naïve and eccentric, but retains an endearing humanity that slowly comes to the fore as he progresses through his investigation. There is wry humour here, and despite his protestations, Boo's grasp of irony is frequently amusing, as is his bemused impatience with others.

But for all the fun in the first third, a sudden shift to darker themes as the plot heats up adds depth and interest to a book that could easily have rested on an intriguing premise. Its exploration of moral grey areas and notions of forgiveness are affecting and thought provoking, while the final sting in the tail is truly earned. Boo is an unusual and surprising novel that should spark plenty of debate.

New York in the mid-1800s is about as far from Heaven as you can get. Over three novels featuring copper-star detective Timothy Wilde, Lindsay Faye has painted an evocative and occasionally unsettling picture of this era of change in the city. In her latest, The Fatal Flame, Faye uses the framework of the historical thriller to examine the political upheaval caused by the feminist movement of the time, while further exposing the rotten heart of the melting pot that was 19th-century New York. This time, a series of fires attract the attention of the dogged detective, and his investigations take him into the world of the Bowery girls who eke out a living on some of the city's most dangerous streets.

Wilde is an ingenious creation; liberal enough for the modern reader, and yet still able to exist in a time and place where attitudes may seem shocking to 21st-century sensibilities. His compassion mixed with his stubborn nature make him seem more than simply a mouthpiece for the author; Wilde is an emotionally honest and authentic figure, wrestling with his own issues while pursuing the job at hand.

The period detail is admirable but never overwhelming, and while Faye helpfully provides a glossary of period slang, she writes in such a readable fashion that the lingo is easily understood from its context. If you haven't experienced New York through the eyes of Timothy Wilde, you're in for a treat.

From centuries past to decades in the future, Paul Johnston's latest Quint Dalrymple mystery, Heads Or Hearts, takes place in an independent Edinburgh during the late 2020s. But an upcoming referendum could see the city return to a united Scotland, a potentially inconvenient outcome for a number of parties. Dalrymple's investigation into a discarded human heart found on one of the city's football grounds and a headless body in a canal soon uncovers a violent conspiracy intended to disrupt the political process.

It must have been hard for Johnston to resist resurrecting the series that made his name back in the 1990s with such rich satirical material available in the aftermath of the independence referendum. Luckily he employs a light hand here allowing the story and characters to remain at the forefront of his story, easing the reader into his densely textured alternative reality. While he lampoons Edinburgh and its citizens to a certain degree, he retains a great affection for the city, employing its history and topography to spark this imaginative and intelligent take on the tropes of the procedural novel.