The suicides of a teenage girl's best friend & mother within weeks of each other, rouse suspicions the deaths may not have been self-inflicted after all.
A delusional alcoholic fantasises about a couple she sees through the train window every day until the woman goes missing and she becomes a potential witness.
Rachel commutes to work by train and fantasises about her neighbours, Megan & Scott, until she witnesses something from the train and learns Megan has vanished.