on an expedition in Alaska – this turns out to be a window to Cittàgazze, exactly like the one Will discovered himself. Shortly afterwards, Lyra's alethiometer (her truth-telling device) is stolen by Sir Charles Latrom in Oxford. Will goes back and confronts Sir Charles but is told he will only return the alethiometer in exchange for the Subtle Knife, located in the Torre degli Angeli, a stone tower in Cittàgazze. Sir Charles is unable to retrieve the knife himself due to the Spectres which infest Cittàgazze and feed on the consciousness of adults. Will and Lyra search the tower but are attacked by another man, an inhabitant of Cittàgazze, who wants the knife for himself. Together they overcome the assailant and win the knife but Will is badly wounded – the little and ring fingers of his left hand are cut off. Meeting the knife's original owner, he reveals to them that Will's injuries are the 'mark' of the subtle knife, which indicate that the knife must pass from him to Will, prompting him to spend some time instructing Will in the use of the knife before he encourages them to leave, intending to commit suicide so that the spectres cannot consume him. As well as being able to cut through to other worlds, the Subtle Knife is also able to cut through any material or object in any of the worlds. Armed with it, Will and Lyra return to Sir Charles’ house and steal back the alethiometer, narrowly evading Sir Charles and his guest, Marisa Coulter. However, the very next morning they are attacked by a group of Cittàgazze children who are furious at them for stealing the knife, led by the younger brother and sister of the man who tried to take it for himself. They flee from the city and are rescued by a group of witches from Lyra's world, led by Serafina Pekkala. Lyra and Will, now escorted by the witches, continue their search for Will's father but are unknowingly being followed by Mrs Coulter and a troop of Spectres. One night, Will, unable to sleep, walks to the summit of the mountain they had been traversing where he encounters a mysterious man. The man realises that Will is the bearer of the Subtle Knife and instructs him to take it to Lord Asriel. However, just as Will recognises that the man is his father, the