With her 30th birthday fast approaching, Kate worries that her age is starting to show in the most unusual of places. She is happy about her budding relationship with new registrar Dr Peter Compton, despite the ridicule she gets from Beth and Lia when they realise she and Peter haven't had sex yet. The nurses at St Margaret's are feeling increasingly under threat from violent patents. Unimpressed with the new, prepubescent security guards, Peter uses his army training to give self-defence lessons to the rest of the staff. Kate's mother, Valerie, surprises Kate with a special birthday visit. Unfortunately, Valerie is more interested in joining Lia and Beth on a boozy night out than spending quality time with her daughter. But Lia and Beth have a surprise - or two - in store for Kate.