Plan a: supress all information.
Plan b: deny everything.
Plan c: eliminate all witnesses and evidence.
Plan d: spread around a little misinformation.
Plan e: spread around a little distracting (possibly unbelievable) truth.
Plan f: kill yourself.
Plan g: try to tell the truth; wait for other conspirators to kill you.
Plan h: try to tell the truth; wait to be institutionalized.
Plan i: contact enemy alien faction; defect to their side.
Plan j: start writing your knowledge in the guise of "science fiction."
Plan k: get drunk and stay that way.
Plan l: pray.