The jarred skull leads Lucy to Bickerstaff's home. The team accepts an invite to the Fittes ball, hoping to snag a rare book from the company library.

With George and Flo on standby, Lucy and Lockwood infiltrate a black market auction where members of the underworld will bid on a priceless artifact.

As Lockwood and Lucy uncover the nature of the bone glass, they come to understand that George's life is in danger — and time's running out to save him.