Spring-heeled Jack is the folklore figure behind two of Charles Dickens's Ghost Club cases. In the first, a cult leader in costume is attacking people in Lambeth; in the second, a far stranger Jack returns and leads you on a rooftop chase.
Dickens makes Spring-heeled Jack the twins' first official Ghost Club case. After saving one of his intended victims, a twin follows his tracks to a cultist warehouse in Lambeth, finds racks of Jack costumes in the sewer lair below, and kills the leader and his followers.
Later a Jack appears who behaves very like the cult leader but is far harder to pin down. He shoots at you while fleeing across the rooftops and fights alongside copies of himself.
Just as the twin is about to finish him, Jack vanishes in smoke, reappears on a nearby roof fully healed, declares that he will never die and takes a Leap of Faith out of sight. Evie later admits there may be something supernatural in their world after all.