The theft of the "Mona Lisa", fake Vermeers, attacks on "Danaë", and Repin's canvas turn the history of art into a tense investigation. Viktor Sidorov will analyze high-profile crimes against masterpieces, explain how forgeries deceived experts, and show the price restorers paid to return damaged works to the audience. The museum hall seems like the safest place for a painting, yet the history of masterpieces is full of thefts, substitutions, and attacks. In the lecture, Viktor Sidorov will gather several high-profile stories where art history intersects with criminology, restoration, and the psychology of mass fame. One of the main episodes is related to the theft of the "Mona Lisa" from the Louvre. The disappearance of the portrait caused an international scandal, turned the investigation into a newspaper sensation, and significantly increased public interest in Leonardo da Vinci's work. Listeners will learn why a crime can change a work's status in culture and make a museum object recognizable far beyond the professional environment. Another line of discussion is dedicated to forgeries. The talk will cover forgers who created convincing "new works" of old masters, including Vermeer. Such stories help to understand the basis of expertise, why specialists can make mistakes, and what role provenance, documentation, technique, and market expectations play in the recognition of a painting. Particular attention will be paid to attacks on works in Russian museums. Rembrandt's "Danaë" in the Hermitage was splashed with acid and suffered severe damage. Ilya Repin's canvas "Ivan the Terrible and His Son Ivan" also endured several attacks. Each such case is followed by years of complex work: restorers must preserve the author's layer, eliminate the consequences of destruction, and make decisions that affect the future life of the painting. In the finale, participants will recall recent museum thefts and discuss why even modern security systems do not eliminate human error, bold calculations, or deliberate vandalism.