"It seems to me that I've been kept in the dark.

You went to the police to demand an investigation into your brother's death, but you did not say anything of the disclosure he made to you yesterday of his daughter's illegitimacy.
Instead of doing so, you only directed suspicion to his man-servant.
Meanwhile your niece, who was placed in your care, disappears to heaven knows where, and you took no steps to inform the police.

You have acted very indiscreetly, Mrs.Pendleton, to say the least." "I did not know--I did not think," gasped Mrs.Pendleton.She endeavoured to commence a flurried explanation of the mixed motives and impulses which had swayed her since her brother's death, but Barrant cut it short with an impatient wave of the hand.
"Never mind that now," he said.

"I have lost too much time already.

Have you no idea where your niece is likely to have sought refuge ?" Mrs.Pendleton shook her head.