The system where, in 2368, a small alien vessel scanned the Enterprise with a beam that erased the identities of everyone aboard, beginning the Satarran deception.
The Epsilon Silar system is the opening setting of the Next Generation episode Conundrum. The Enterprise is investigating a series of subspace signals when an unfamiliar ship approaches and sweeps it with an intense scanning beam.
In an instant the crew forget who they are, though their skills remain, and the computer's personnel files are selectively wiped. A new face is now among them, Commander Kieran MacDuff, listed in the altered records as first officer.
Reconstructed orders tell them the Federation is at war with the Lysian Alliance and that they must destroy its central command. MacDuff is in fact a Satarran agent, and Picard's unease at attacking a hopelessly outmatched enemy exposes the lie.