When it was shot down by an Autobot battalion during entering Earth's atmosphere. On entry, it split into two pieces. Starscream investigated the crash site. However, he neglected to record the location of the crash site but instead memorized the coordinates.
After Airachnid "rejoined" the Decepticons she informed Megatron of the Harbinger's cargo and was sent along with Starscream to locate the cargo. She then activated the ship's computer systems to find where the weapon was stored. This allowed the Autobots to locate the ship. After traveling to the other half of the ship, she located the weapon and removed it from the ship.
After a streak of bad luck, Starscream eventually returned to the location of the Harbinger. Inside, he was disappointed upon discovering that the ship did not contain any energon, but did discover a functional laboratory, containing five unused Protoforms. By using some of his own energon, Starscream was able to engineer five perfect clones of himself out of the protoforms.
After four out of the five were destroyed, the remaining clone returned to the Harbringer, specifically the laboratory, where Starscream killed him after it planned to betray him.