Stock-exchange brokers (sellers) (plaintiffs) agreed to sell and deliver an Oregon Short Line Railroad bond to another group of brokers (buyers) (defendants). A third party provided the sellers with an Oregon & California Railroad bond by mistake. The sellers did not realize the mistake and used a messenger to deliver the bond to the buyers’ office. The office’s delivery room contained a slot and a closed window. The buyers’ employees were located in a room adjacent to the slot and window. After placing the bond in the slot, the sellers’ messenger quickly left the building. One of the buyers’ employees realized that the bond had been delivered by mistake. The employee opened the window and handed the bond to an unidentified messenger, mistakenly believing him to be the sellers’ messenger. The unidentified messenger took the bond, but never returned it to the sellers. The sellers sued the buyers for conversion, claiming that the buyers had an absolute duty to return the bond to the sellers. The sellers also claimed that if negligence was at issue, the buyers had not exercised due care in attempting to return the bond. The buyers claimed that they were not liable for the lost bond, because they had only a duty of due diligence and had exercised all care required of them. A lower court ruled in favor of the sellers.