Once Upon a Time in the West

When a young woman dies from cardiac arrest due to digoxin poisoning, Castle and Beckett must infiltrate her last-known location – an Arizona dude ranch. In New York, Ryan and Esposito learn the victim was researching the Peacock Boys, train robbers who were killed in 1893. The gold the robbers were looking for may have been in the wrong place. Instead of the gold, Castle and Beckett find skeletal remains. Castle also finds the killer at the dude ranch. With the case solved, Beckett decides to stay with Castle at the ranch a little longer, as part of an impromptu honeymoon.