Staines was with Anna and said he had something "impertinent" to ask her. That made her nervous and sad for some reason.
Staines then asked about Wells, much to her surprise. He explained (without violating Crosbie's confidence) a bit about why he thought Anna and Carver might be acquainted. He wanted to hear the whole story of the robbery Crosbie claimed happened.
Anna asked if Crosbie was in Hokitika, and Staines said he couldn't say. While rubbing her tummy, Anna said that was fine, but she had a message for him …
The blurb that introduces the section indicates that she then told him the whole story of her acquaintance with Wells, Carver, and Lydia.