Stand in front of Hans Holbein’s 1533 masterpiece The Ambassadors and you see wealth, cutting-edge science, and confident diplomacy. Step to the side and a stretched smear across the floor resolves into a human skull. This episode is a forensic investigation of a single oak panel painted as Elizabeth I was born, the Reformation was fracturing Europe, and Henry VIII was breaking with Rome to marry Anne Boleyn.

We identify the two men, French ambassador Jean de Dinteville, aged 29, and Georges de Selve, a 25-year-old bishop on a secret visit hidden from French officials, standing on a replica of the Westminster Abbey coronation pavement. Then we work down the two-tiered table: a celestial globe set to Rome’s latitude, a sundial showing two different times, a shepherd’s dial casting an impossible curved shadow, an upside-down terrestrial globe, a lute with a snapped string, an arithmetic book open to the chapter on division, and a Lutheran hymnal. We examine Edgar Samuel’s 1962 theory that the anamorphic skull was meant to be viewed through a perspective glass, the disputed 1997 restoration, and the tiny crucifix hidden behind the curtain.

• Why almost every scientific instrument in the painting is broken or misused
• The theory that Anne Boleyn herself commissioned the work as a diplomatic gift
• Law facing grace: the optimistic reading of the open hymn pages
• Mathematician John Sharp’s critique of the National Gallery’s skull reconstruction
• How a memento mori becomes a message of hope at the edge of the frame