Castle and Beckett arrive with Ryan and Lanie at a ratty single room occupancy hotel, and stand over a tub of black liquid, staring at the body of a dead woman floating inside. Esposito holds up an empty can of 10W-40 motor oil. Looks to us like more than Calgon took her away!Beckett and Castle talk with the jaded night clerk. We quickly surmise that he’s no help, except to say whoever rented the room paid cash for a five-day stay.At the morgue, Lanie explains that the unidentified female is in her early-40s, wearing a wedding ring without an inscription. She was first knocked out with a hit to the head before drowning in the oil. Tox screens are negative for drugs, alcohol and recent sexual activity. But one of the glasses of wine tested positive for Remian, a sleeping pill. Lanie also found a Metro-North ticket stub—the victim was from out of town, we realize.