The Medium and the Missing Couple
Foucault's PendulumBelbo's visit to a Picatrix séance links the Plan to a medium who vanishes, while the police dismiss the episode as drug-related confusion.
increasing
Bearing strength in each event
decreasing
An Occult Performance

Echoes in a Trance
A startling phrase
At a Cagliostro séance, a medium speaks of six seals, a hundred-and-twenty-year wait, and thirty-six invisibles. Belbo recognizes ideas from the Provins message.
Police observation
De Angelis is present and notices Belbo's interest. He interprets the medium's words as material absorbed from occult publications and rehearsed in trance.
A Sudden Disappearance

The Missing Medium
An empty apartment
De Angelis reports that the medium and her companion have vanished, leaving a ransacked flat. The detective cannot tell whether they fled, were threatened, or were harmed.
Competing accounts
Belbo accepts a plausible story about a drug-deal dispute, but later wonders whether someone removed the pair to hide knowledge of the Plan.
The Suspicion Persists

An Unclosed Possibility
A reasonable explanation
The police attribute the episode to drugs and occult reading. Their account ends the investigation without proving what happened.
A conspiratorial alternative
Belbo wonders whether the séance exposed someone who knew too much. The ambiguity strengthens his tendency to imagine a cover-up.
Several years after Ardenti's disappearance
Two days after the séance
After Belbo writes to Casaubon in Brazil