Robert Holt
An unemployed clerk enslaved by the Beetle's mesmerism, used as burglar, messenger, and later captive.
The Beetle / the Arab / the Woman of the Songs
A shape-changing figure associated with an Egyptian cult of Isis and determined to destroy Lessingham.
Paul Lessingham
A celebrated politician haunted by his youthful captivity and escape from the cult.
Marjorie Lindon
A politically engaged young woman loved by Lessingham and Atherton, later hypnotized and abducted.
Sydney Atherton
An inventor, chemist, and rejected suitor whose volatile experiments and courage aid the pursuit.
Augustus Champnell
A confidential agent who organizes the late investigation and narrates the chase.
Geoffrey Lindon
Marjorie's domineering father, hostile to Lessingham and determined to control her marriage.
Dora Grayling
Marjorie's perceptive friend, sympathetic to Atherton and eventually his wife.
Percy Woodville
Atherton's acquaintance, nearly killed during an experimental demonstration.
Louisa Coleman
A neighbor whose observations help trace the Beetle and Marjorie from the abandoned house.