It's the finale of Doctor Foster already tonight, how did that happen?! I guess it is just five episodes but after waiting two years for a second season it feels like it's over far too soon. Tonight sees Gemma (Suranne Jones) going to extreme lengths in order to come out on top and win back her old life, but will she find herself going too far this time? If tonight's finale is anything as gripping and downright brilliant as season one's finale, we're in for a treat.