Martinez mixes mathematics and murder mystery in a clever way. While it’s not necessary to know mathematical theory to read the book, mathematicians can certainly get more out of it. Most of the theories are explained along the way, and those who don't have any interest in higher mathematics might find it a little tedious, although the explanations are brief.

The main character is a young Argentinian mathematician who arrives to stay at Oxford for a year. Soon his landlady is murdered in a strange manner, and he finds himself near the center of a mysterious series of murders. The serial killer has sent a note to Arthur Seldom, a famous mathematician and friend of the landlady's family. The note contains the date and a symbol of a circle. One chapter of Seldom’s book on math discusses how mathematics could be related to serial killers. That chapter is believed to be the reason why someone would challenge Seldom to solve a mathematical murder mystery. Seldom takes the main character under his wing, and together the two mathematicians try to solve the mystery before more people die.

The main character is quite a colorless man. We don't find out much about him; even his name seems to be too difficult for the British to pronounce, so it's never revealed. Seldom comes across as cold, more interested in solving the intellectual puzzle of the symbols connected to the murders than actually saving lives. Police inspector Petersen, portrayed as somewhat unable to think outside the typical police-procedural box, seems more like a real person than Seldom. Only two other characters are seen more than once: Beth, the landlady's granddaughter, and Lorna, the main character's tennis partner and a nurse, who quickly becomes his lover. With her interest in crime fiction and unrevealed history with some other characters, Lorna feels more flesh and blood than any of the other characters.

Martinez writes from the first person point-of-view, allowing him to leave his main character vague while letting the reader identify with him easily. On the other hand, the character is not a memorable one.

Martinez’s style conjures more the gentlemanly atmosphere of Conan Doyle or Agatha Christie than the more modern style, where the protagonist is often in personal danger. There is an absence of urgency, and any tension is an abstract worry for the next possible victim or outwitting the killer. Martinez also makes some interesting and funny observations about the British from a foreigner's point of view.

Sonia Soto's translation is first-class. The translation is in clear British English, and there is no sign of the Spanish word orders.