Four stars only because I would have liked it to feel a little more finished at the end-- yes, I know it's the first of a series, but even so. I loved the setting and characters-- I used to live in the East End, and it all felt very authentic to me (especially as an American who went to school in London, there was a lot I recognized). It was a great read, thrilling, and I thought the revelations were well-paced. 
 In the end, it's made me really eager to read the next book, which after all was the point.