The Voltron Force knows the truth about Zarkon, but they lack proof. Merely keeping an eye on him at Galaxy Garrison just isn't cutting it. Taking more initiative, Keith and Lance secretly follow Zarkon around – ultimately getting all the way to Lotor, Haggar, and Castle Doom. Unfortunately, staying hidden from so many enemies isn't possible for very long. Just getting out of alive won't be easy for Keith and Lance. Things only get worse back at Galaxy Garrison, too.