Why was Paul imprisoned in Philippi?

In Philippi, Paul encountered a servant girl who had a spirit that allowed her to predict the future. Her masters had been using this ability to earn money by having her tell fortunes. When Paul, disturbed by her repeated shouting after him and his companions, commanded the spirit to leave her, she was immediately freed from the possession that had made her valuable to her owners.

It was the loss of income that followed the healing of this possessed girl that triggered the events leading to Paul's arrest. Her owners, realising that their source of profit was gone, seized Paul and Silas and dragged them before the city authorities on trumped-up charges of disturbing the peace, which resulted in their being beaten and thrown into prison.

Preaching in a synagogue and disputes with Roman guards do not appear in this account, and there is no record of temple theft connected to Philippi in the narrative; those alternatives describe events that either did not happen or belong to different episodes in Paul's ministry. The imprisonment traces directly and specifically to the deliverance of the possessed girl and its financial consequences for the men who exploited her.

When an examination asks for the cause of an imprisonment in Acts, trace the narrative back to the specific act that provoked the accusers, rather than assuming it was simply preaching or general conflict with authority.