S7, E11: Catherine's testimony in court is not enough to convict a killer suspected of murdering his own mother. Adam Novak, with whom Catherine had a brief romantic encounter, is the lawyer who represents the killer and secures his freedom. As a result, Catherine and Nick leave Las Vegas in order to tie the killer to another crime and put him behind bars for good. Meanwhile, Grissom says goodbye to his colleagues and heads east for a teaching sabbatical. (TV-PG)