Jack Jumps In is the seventh episode ever made in Season 6.
Thomas takes an eager front-loader named Jack to help the Pack clear ground for railway lines. Jack quickly gets accustomed to his work, but when he foolishly tries to take some rocks up a hill, he loses his balance and rolls down the hill. Jack is upset and Miss Jenny is cross, but Isobella, Alfie, and Thomas are sympathetic.
- Thomas leaves with the wellwagon after delivering Jack, but in the close-up of Jack, the wellwagon is still behind him.