Thought angels were all sweetness and light? Trussoni invites us to think again in this, her second book, a fascinating thriller spanning continents and millennia, fact and fiction.

The story begins in (more-or-less) present day New York. Our heroine, Evangeline, is a nun at St. Rose Convent in the Hudson river valley, home to the Franciscan Sisters of Perpetual Adoration, a convent that takes a somewhat unnatural interest in all things angelic. Evangeline, who joined the convent aged 12 after her father moved them both halfway across the world from their native France following the mysterious and untimely death of her mother, is now in her early 20s, comfortable in her everyday religious routines.

Our hero, Verlaine, a PhD candidate absorbed in his own unusual interest - Abigail Rockefeller - finds himself in the employ of a particularly unsettling gentleman (who just happens to be part of an ancient Nephilistic (half human, half angel) family, though Verlaine is initially unaware of this) who is keen to know more about some of Rockefeller's correspondence with the Franciscan sisters. As a result, a slightly harried Verlaine finds himself reluctantly trespassing at the convent for a bit of covert research, where he bumps into Evangeline. From this point on their stories become entwined as a whole new world of angelology (the study of angels, a real branch of theology) opens up to them. The reader is thus plunged into an exciting, fast-moving tale of ancient feuds and the revelation of startling truths about the world, follwoing our heroes as they lurch from one disaster to the next just in the nick of time, solving mysteries as they go.

This impressive book by American writer Trussoni may only be her second, but she lives up to the formidable reputation she established following the publication of her first book (the non-fiction Falling Through the Earth: A Memoir, which was chosen by The New York Times as one of the ten best books of 2006 and won the Michener-Copernicus Society of America Award, Elle Magazine's Reader's Choice Award for April 2006 and was chosen as a Book Sense Pick for March 2006). Following its release in hardback, Angelology, her first novel, won her yet more critical acclaim, becoming a New York Times Bestseller, and the film rights were bought outright with Will Smith, Marc Forster (director of Quantum of Solace) and Michael Goldenberg (who adapted Harry Potter and the Order of the Phoenix) already signed up to the project, due for release in 2013.

The good news is that the first part of the book - where we get to know our heroes and their Nephilistic nemeses - is thoroughly enjoyable, where each short and perfectly formed chapter leaves you desperate for more. The bad news is that Trussoni doesn't keep this up for the other two parts that follow, which fit together about as well as Lego does with Duplo - they sort of fit, but it's a bit clunky.

One of the strengths of the story is its plausibility, bolstered by its grounding in biblical stories and classical art and literature. Not to suggest that Trussoni’s powers of imagination are in any way lacking, but Trussoni has clearly drawn from her considerable personal expertise in these matters to produce this richly detailed work. Not only does she have a personal interest in angels, but her depictions of the cave in the Rhodope mountains in Bulgaria (into which, legend has it, the fallen angels were banished) no doubt benefited from her personal Bulgarian connections (she briefly lived in Bulgaria with her Bulgarian husband); and the detailed depiction of the convent is clearly informed by her great aunt's position as a Franciscan Sister of Perpetual Adoration at the Saint Rose convent in Wisconsin, a convent that resembles its fictional counterpart not just architecturally but also in that it was burnt down at one point.

Whilst it's true that this tome contains an awful lot of interesting ideas about angels and their study, at the same time one can't help feeling that 300 or so pages could easily be dispensed with without doing significant harm to the narrative flow, not least because as it stands, Angelology must surely be a contender for the next survey of which books may protect you from a bullet (don't try this at home, kids), coming in at a whopping 642 pages. She could start by dispensing with the vast quantities of fairly nauseating Mills & Boon-esque waffle concerning our protagonists.

It’s no surprise that the film rights have been snapped up as it seems ripe for film adaptation and might perhaps work better on the silver screen, which inevitably condenses and abridges even the most rambling of tales - though there is always the risk that the story might be told as a (somewhat ghastly) love story rather than the clever and surprising thriller it really is.

Perhaps it's worth waiting to catch Angelology in film form, although readers with good upper body strength (or, of course, an e-reader), capacious hand luggage and a perseverant streak may wish to look out for it in its hefty paperback form.