Book The Second: Riches Chapter 23 Mistress Affery makes a Conditional Promise,

Left alone, with the expressive looks and gestures of Mr Baptist,
otherwise Giovanni Baptista Cavalletto, vividly before him, Clennam
entered on a weary day. It was in vain that he tried to control his
attention by directing it to any business occupation or train of
thought; it rode at anchor by the haunting topic, and would hold to no
other idea.

As though a criminal should be chained in a stationary boat
on a deep clear river, condemned, whatever countless leagues of water
flowed past him, always to see the body of the fellow-creature he had
drowned lying at the bottom, immovable, and unchangeable, except as
the eddies made it broad or long, now expanding, now contracting
its terrible lineaments; so Arthur, below the shifting current of
transparent thoughts and fancies which were gone and succeeded by others
as soon as come, saw, steady and dark, and not to be stirred from its
place, the one subject that he endeavoured with all his might to rid
himself of, and that he could not fly from.

The assurance he now
had, that Blandois, whatever his right name, was one of the worst of
characters, greatly augmented the burden of his anxieties. Though the
disappearance should be accounted for to-morrow, the fact that
his mother had been in communication with such a man, would remain
unalterable.

That the communication had been of a secret kind, and that
she had been submissive to him and afraid of him, he hoped might be
known to no one beyond himself; yet, knowing it, how could he separate
it from his old vague fears, and how believe that there was nothing evil
in such relations? Her resolution not to enter on the question with him,
and his knowledge of her indomitable character, enhanced his sense of
helplessness.