Sweet Valley High - Season 1 Episode 9 -

When Jess leaves Elizabeh stranded at the Moon Beach, she has no choice but to hitch a ride with Todd's motorcycle (or miss her deadline). On the way they get into an accident and while Todd is virtually unharmed, Liz is left with a coma. Guiltridden, Jess stays by her side until Liz recovers. However, she seems to have undergone a personality change, literally acting more ""Jessica"" than Jessica.