Three years have passed since the events of The Day Watch. His wife and daughter spending the summer on a dacha not far from Moscow where Anton is working when his boss Gesser reveals he has received an anonymous note. An Other has exposed the truth about their kind to a human, and now intends to convert that human into an Other.
The note has been sent to Zebulon and to the Inquisition's offices in Berne - a place whose address only the highest level of mages and sorcerers know. Now cooperating, the Night Watch and the Day Watch, along with an Investigator from the Inquisition, seek to unmask the culprit. Anton will represent the Night Watch, while the Day Watch is sending High Vampire Kostya Saushkin, once Anton's teenage neighbour.
Installed in the apartment complex to which the letter writer has been traced, Anton begins to investigate the residents one by one. Reviewing the dossiers of the building's inhabitants, Anton comes across a familiar - albeit much younger - face. Could Gesser be trying initiate his son as an Other?