How did Bod escape the pawn shop in Neil Gaiman's "The Graveyard Book"?

Poor Bod has been locked in a back room by a greedy pawn-shop owner called Abanazar Bolger. Bod has in his possession a valuable brooch. Bolger knows just how valuable this piece of jewelry is, but isn't prepared to pay Bod a fair price for it; he'd much rather steal it from him. He'd also dearly love to know where Bod found the brooch so he can get his grasping hands on more treasure.

Bod hoped to pawn the brooch to buy Liza Hempstock a gravestone. When she was alive, Liza was partially drowned and then burned at the stake as a witch. Although she really was a witch, Bod takes pity on her; he thinks it rather unfair that Liza doesn't have a gravestone of her own, so he steals the brooch from the Sleer, and for the first time, ventures outside the confines of the graveyard to see if he can raise some money for the young witch spirit.

Meanwhile, back in Bolgar's pawn-shop, Bod tries to figure out a way to escape. He can move through walls in the graveyard alright, but in the world outside the graveyard, it's impossible. Thankfully, Liza's on hand to help Bod out of a jam. Immensely grateful at Bod's risking his neck to buy her a gravestone, she says a few magic words, and Bod is able to fade away, leaving Bolger and his accomplice scratching their heads when they unlock the back room door.

How did Bod escape from the pawn shop in The Graveyard Book?

Bod manages to escape from the evil clutches of the pawn shop owner, Abanazar Bolger, thanks to the help of Liza Hempstock. Liza was once a witch; indeed, that's why she was killed. But, despite her evil reputation, she nevertheless helps Bod escape from the pawn shop, out of gratitude for Bod's wanting to buy Liza a gravestone. As a witch, Liza was buried without a gravestone, and Bod thinks that's just so unfair. So he goes off to see Bolger in the hope of getting a fair price for the valuable brooch he obtained from the Sleer. He plans to use the proceeds to pay for the witch spirit's gravestone.

Unfortunately, all doesn't go according to plan. Bolger and his greedy partner-in-crime lock Bod up in a back room until he reveals where he got the brooch and where they can lay their hands on some more treasure. Thankfully, Liza is on hand to save the day. She utters a few magic words and—hey presto!—Bod slowly vanishes into thin air, leaving Bolger and his accomplice looking pretty confused when they open the back room door and find that he's gone.