Stardate: 41242.4 The crew of Enterprise discovers another of Dr. Soong's androids while attempting to investigate Data's past. After they reassemble the newly found android, which also exactly resembles Data, they learn the android is named "Lore". Lore tells the crew he is Data's older more perfect brother. However, the crew soon learns why Lore was disassembled, as Lore soon leads the dreaded object known as the Crystalline Entity to Enterprise's location for his own evil purposes, and the destruction of Enterprise and Data.

While testing a new nuclear bomb defusing team at the Phoenix Foundation, a deadly explosion kills three men. Pete blames himself for not inspecting their equipment better and resigns from his job out of guilt. However, Pete is replaced by a not-so-trustworthy man-one who may have been connected to the explosion.