What did Crispin see in the forest the night after his mother's burial?

Crispin sees a stranger with grey hair talking to Richard Aycliffe, the steward.
According to the text, Crispin sees the stranger hand a document to Richard Aycliffe. The conversation, however, is confusing to Crispin.
When Richard Aycliffe is handed the document, he exclaims after reading the contents. Next, he asks when the event spoken about in the document will occur.
The stranger answers that he is hopeful the event will happen soon. To this, Aycliffe asks whether he should act immediately. The stranger's answer suggests that there is a great danger in delaying. He reminds Aycliffe that he is kin to one of the individuals mentioned in the document.
The contents of the document are revealed at the end of the novel, when Crispin confronts Aycliffe. Accordingly, Lord Furnival's death would have precipitated a power struggle for the highest position in the Furnival empire. Even as a illegitimate son, Crispin was still seen as a threat to all the power players angling for Lord Furnival's position. Aycliffe himself felt threatened by Crispin. This is why he declared the young boy a wolf's head, in effect putting a death sentence on him.