Purvis tells the story in Dr. Smedley’s book as follows:

One day while Basil was plowing the field some distance from the house, he was seized by slave catchers, beaten and carried to Bristol, about three miles distant. Here he was thrown into a cell used for criminals. I had just returned from the city and was eating my supper when a neighbor’s son came in great excitement to tell me that Basil had been carried off. I hastened to the scene and from farmers learned the details of the outrage. Burning with indignation, I hurried to Bristol where I found the captors and captive.

An excited crowd of people had gathered and I spoke to them and succeeded in enlisting their sympathies for the poor victims. After conferring with the slave holders it was agreed we should meet at Bristol at seven o’clock in the morning to go before judge Fox, at Doylestown. I then returned home to secure the safety of Basil’s brothers. They had heard of Basil’s capture and had been pursued to my house by a party of the same men, led by a local constable. These were now in a field close to my residence, evidently deliberating how to proceed. I placed a double-barreled shotgun, heavily charged, in Charles’ hands, and he walked out in front of the house and defied them. The slave catchers, thinking doubtlessly that discretion was the better part of valor, instantly departed. Under cover of darkness I was able to convey Charles, his family, and William to the home of my brother Joseph and that night he drove 40 miles inland [Ed. Note: To Reading?] and left them at the home of a friend.

The next morning at 6 o’clock I was on my way to Bristol when I met a woman who informed me that at 5 o’clock a wagon passed her house and she heard Basil cry out : ‘Go tell Mr. Purvis they are taking me off.’ The object of this movement was to deceive me in regard to time and enable them to appear before Judge Fox and by ex parte testimony have the case closed and the victim delivered to them. I hurried home, harnessed a fast trotting horse and pursued them, I left instructions that Basil’s wife and children should follow in another carriage.

I continued to the home of William H. Johnson, the noted Abolitionist, who went out and spread the alarm among anti-slavery people. I arrived at Doylestown fully an hour before Basil and his captors, who was surprised to see me. I at once secured the services of the ablest lawyer in town, Mr. Ross, son of a judge, who won postponement upon claim that Basil’s papers were in the hands of friends in Columbia, Pa.

Mr. Purvis then tells of the activities in the next two weeks. David Paul Brown, noted attorney, offered his services to Basil without cost. The Underground recruited three squads of men to occupy roads leading from town. In the event Basil was turned over to the captors, these squads “would take adequate means to liberate him.” An effort was made to buy Basil from the captors. Each time the money was raised, the price went up. When the price reached $1,000, Basil said: “No more offers, If the decision goes against me, I’ll take my life in the court room.”

Mr. Brown, the lawyer, was making preparations on his own. His first move when the court opened was to demand that claimants show proof that Maryland was a slave state. The claimant’s young lawyer was stunned, but given 10 minutes, presented a compilation of the laws of Maryland. Brown took the position that this was no authority since the book was old and the law might have been repealed. When this argument could not be met, the judge dismissed the case.

Mr. Purvis arid Basil left the courthouse as speedily as the crowded audience would permit. The slave hunters were even faster. As the freed man amid his protector got in their carriage, they appeared with a new warrant. Mr. Purvis lashed his horse and sped out of town. They had not gone far when they met one of the Underground squads set to wait there. Basil leaped out and went over the fields with them. Mr. Purvis continued his dash home, the slave hunters following him, only to find Basil well on his way to New York.

https://www.berkshistory.org/multimedia/articles/the-underground-railroad/