When Kewper learned that the First Doctor, Ben Jackson and Polly Wright were friends of Joseph Longfoot, he gave them food and lodging, at least until he learned from the stable boy that Longfoot had been murdered. He sent the boy to fetch the Squire and gave up Ben and Polly to him.
Kewper approached Captain Samuel Pike with an offer for him to do business with the Squire. While on Pike's ship, he informed the Doctor that Ben and Polly had been arrested for Longfoot's murder. Fearing for the town's safety when Pike went in search of Avery's gold, Kewper and the Doctor planned an escape from the ship. After fooling Jamaica with card tricks, they escaped in Kewper's boat.
When they reached Ben and Polly, revenue officer Josiah Blake accused Kewper of being in league with the Squire. Kewper ran away. He reported Pike's trickery to the Squire and told him about Avery's gold and convinced him to try to find it themselves. They came across the Doctor, Ben and Polly in the church crypt. Kewper threatened the Doctor's companions to find out Longfoot's secret, but he was stabbed and killed by Cherub. (TV: The Smugglers)