At the Convent of Sweet Mercy young girls are raised to be killers. Sweet Mercy hones its novices’ skills to deadly effect: it takes 10 years to educate a Red Sister in the ways of blade and fist. But even the mistresses of sword and shadow don’t truly understand what they have purchased when Nona Grey is brought to their halls as a bloodstained child of eight, falsely accused of murder, guilty of worse.

Fantasy novels about assassins are ten-a-penny, so if you want to stand out in this overcrowded genre you’re going to have to do something pretty special. Though it is not without its flaws, I can confirm that Red Sister by Mark Lawrence is something pretty special.

In essence, this is a fantasy boarding school novel. Much of the action takes place in the Convent of Sweet Mercy, where young girls attend classes, forge close friendships, sleep in dormitories and sneak around after lights out. It will be a formula familiar to many readers, but Lawrence ensures his world has edges sharp enough to make sure the familiarity doesn’t breed boredom.

It’s a shame that the middle of the book becomes dull and repetitive. However, it’s worth getting through these slower moments to experience Lawrence’s skill when it comes to action scenes.

There are also moments when Lawrence falls prey to the fantasy writer’s worst enemy: the info-dump (in which writers give lots of information about their fantasy world in one long section). Some of the concepts he has come up with are quite complicated and he seems unsure as to how best explain them, so he runs to paragraphs explaining the same thing in a few different ways in the hope readers will understand.

But, luckily, the world Lawrence has created is fascinating – and his characters endearing. You will have to suspend your disbelief in regard to the characters’ ages (no eight-year-old talks like that) but Nona’s spiky attitude, witty comebacks and vulnerability will quickly bring you round to liking her. The only problem is that she verges on Mary-Sue territory – the perfect character who never gets anything wrong – and I hope Lawrence takes the chance to develop her character further in the sequel.

I also loved that the majority of the large cast are female. As such Lawrence presents the reader with a wide range of women – women who are brave, bold, frightened and flawed. In a genre that is often dominated by male characters wielding swords, it was refreshing to see women take the lead.

This book has its flaws but it opens up a fantasy world that I am more than happy to spend time in.

Red Sister is dark and bloody, marking the beginning of a new fantasy series that I will definitely be keen to continue reading.

Many thanks to HarperCollins for a copy of this book in exchange for an honest review.