Lu Yin started his career as an Imperial Clerk () and Gentleman in the Selection Bureau of the Imperial Secretariat () during the reign of
Sun Quan, the founding emperor of
Eastern Wu.
Sun He, Sun Quan's third son and
heir apparent, heard of Lu Yin's talent and treated him exceptionally well. Around the 240s, there was
a power struggle between Sun He, the Crown Prince, and his fourth brother
Sun Ba, the Prince of Lu, over the succession to their father's throne. While Sun He became worried that his father would depose and replace him, Sun Ba became increasingly set on seizing the position of Crown Prince from Sun He. Each of the two princes had a faction supporting him. During this time, Sun Quan considered replacing Sun He with Sun Ba so he privately asked Yang Zhu (), one of Sun Ba's supporters, about his thoughts on Sun Ba. Yang Zhu sang praises of Sun Ba and nearly convinced Sun Quan to replace Sun He with Sun Ba. A servant who eavesdropped on the private conversation between Sun Quan and Yang Zhu secretly reported what he heard to Sun He. At the time, Lu Yin had been assigned to a position in Wuchang (武昌; present-day
Ezhou,
Hubei) and was about to leave the imperial capital,
Jianye (present-day
Nanjing,
Jiangsu). When he went to bid Sun He farewell, Sun He publicly declined to meet him. However, Sun He later disguised himself and sneaked into Lu Yin's carriage to discuss with him how to safeguard his position as Crown Prince. They decided to seek help from Lu Yin's relative
Lu Xun, a senior general who later became the third
Imperial Chancellor of Wu. Lu Xun then wrote a
memorial to Sun Quan to dissuade him from replacing Sun He with Sun Ba. Sun Quan was surprised to receive Lu Xun's memorial and he thought that Yang Zhu revealed the details of their private conversation. When Yang Zhu insisted that he did not, Sun Quan ordered him to find out how Lu Xun knew about it. Yang Zhu then deduced that it must have been Lu Yin who told Lu Xun in Wuchang. Sun Quan then sent a messenger to check with Lu Xun, who confirmed that it was Lu Yin who told him. Sun Quan then ordered Lu Yin to be arrested and interrogated. While being tortured during interrogation, Lu Yin refused to reveal that it was actually the servant who told them, so as to protect Sun He and prevent him from being implicated. Instead, he lied that it was Yang Zhu who told them about it. Sun Quan then ordered Yang Zhu to be arrested and interrogated as well. Yang Zhu, unable to withstand the torture, falsely admitted that he told Lu Yin. As Sun Quan had already suspected that it was Yang Zhu who leaked the secret, he became even more convinced after hearing Yang Zhu's false confession, so he executed Yang Zhu and released Lu Yin. ==Pacifying rebellions in Jiao Province==