Chapter 6 of shadowshaper summary

In Chapter 6, Sarah goes to the Junklot where Manny is playing dominoes with his friends. A member of the group asks whether Sierra is having problems at school. She asks Manny about Vernon. He says that Vernon is missing. Sierra goes to paint. Robbie comes, and they talk about the fact that Robbie had disappeared. Sierra tells him he can make it up by working on the mural. His work impresses her. He tells her that he painted the mural that is disappearing. He wants to say something else, but he cannot. They discover that they both saw the teardrop. Sierra tries to get Robbie to tell her about the shadowshapers. Then, Bennie calls and tells Sierra that Wick is an anthropology expert who studies spirituality systems and worked at Columbia before disappearing. Sierra can find out more at the Columbia anthropology archive. Sierra tells Robbie that they will finish the conversation later and goes to Neville who agrees to drive her to Columbia.