Dangerously unstable and unpredictable "treacherous winding roads" - unreliable
Tending to betray; especially having a treacherous character as attributed to the Carthaginians by the Romans "the fiercest and most treacherous of foes"; "treacherous intrigues" - punic, perfidious
See also: dangerous, treacherously, treachery, unfaithful, unsafe