A few days of investigation and research. Talking with the apartment manager reveals that all of the tenants -- not just the missing Abigail -- are three months behind on their rent and facing eviction. Curious.
Interviewing the neighborhood business indicates that the tenants have completely withdrawn from the community. They have not patronized shops, bought groceries, etc. Curious.
Sir Richard receives a family request to negotiate a business deal back in Boston and had to leave. The transient population of Manhattan is safe, for the time being.
The rest of the trepid heroes -- George Platt, Evelyn Joans, and Herr Doktor Professor Victor Hawkins -- decides that a night spent in the missing woman's apartment might provide insight.