Beloved characters deserve fitting farewells, and Sara Sidle (Jorja Fox) receives one tonight from CSI.

The episode, titled “Goodbye & Good Luck,” vividly makes you feel Sara’s disillusionment with her work. In witnessing an eerie case of domestic abuse, she remains oddly remote.

The real crisis for Sara, however, comes from familiar sources. Returning in creepy style are Marlon West (Douglas Smith) and his genius little sister, Hannah (Juliette Goglia).

Last time out, Marlon got away with murder with Hannah’s help.

This time he is implicated in a young woman’s plunge from her dorm room. (The episode airs at 9 p.m.on WKMG-Channel 6.)

In the previous case, Hannah got under Sara’s skin. The little girl is needling Sara again, and Goglia pulls off that task brilliantly.

As Sara seeks justice, the episode takes twists that are clever or harrowing. Can Sara finish the case?

The haunting cinematography heightens Sara’s out-of-sorts outlook. CSI has won fans as a smart procedural, but the show also depicts personal stories with devastating payoffs.

Fox plays Sara’s sadness with such wrenching and relatable feeling that this episode becomes one of the most satisfying hours you’ll see this season.