déflorer

Literally to deflower (take someone's virginity), but far more commonly used today in the figurative sense of spoiling or taking the freshness out of a subject, idea, or surprise — déflorer un sujet, déflorer une intrigue.

• Je ne veux pas déflorer l'intrigue du film. — I don't want to spoil the plot of the film.
• Cet article défleure déjà le sujet de la conférence. — This article already gives away too much of the conference topic.
• Il a préféré ne pas déflorer davantage le débat. — He preferred not to give away more of the debate in advance.

In modern journalism and everyday speech, déflorer un sujet/une intrigue (to spoil a topic/plot) is the sense actually in use — the literal meaning is dated and rarely the intended one in context.