From School Library Journal
The unkempt old house, an eyesore in a gentrified Canadian city neighborhood, reminds 15-year-old Cass of a half-remembered dream. Its cheap second-floor flat is such a godsend that he and his improvident single mother, Alison, don't mind their reclusive, possibly sinister landlord, Mr. Magnus, living on the floor below. While Alison plunges into her long-postponed thesis on William Blake, Cass unpacks and observes neighborhood bullies extort cash from young children and play nasty pranks on Mr. Magnus. When Cass takes a job as an usher in a run-down movie theatre, he endures abuse by the head usher. Meanwhile he ponders the significance of pictures left in his flat--a painting of a snake swallowing its tail, a photograph of young Mr. Magnus in World War I uniform--and of the dreams that haunt him, dreams of muddy trenches, of gunfire, gas, blood, pain, and fear. Curiosity and sympathy draw Cass and his new friend Maddy into the old man's obsession with alchemy, which gives the book its title. While the villains seem implausibly malicious, the main characters are vivid and three-dimensional, and the atmosphere of decay and disorder is made palpable by sensuous writing.
While this is classified as a children's/teen book, I think older readers will enjoy the story as well. A great mystery story incorporating tales of WWI and the ancient "science" of alchemy. The main characters are very likeable and demonstrate wisdom beyond their years.