It's Mac's last day and Sue and Caroline are struggling to cope with the thought of losing him. While Sue offers to kill in order to keep Mac in the hospital, Caroline spends most of the day trying to find fault with Sheffield in order to deter him from leaving. Meanwhile Martin finds himself in a tricky situation when he reads a personal letter of Guy's and discovers that not only is Guy adopted, but that his real mother was called Joanna Peerson – the surname of whom also happened to be the maiden name of Joanna Clore. Unaware that his mother and work colleague are one of the same, Guy has no qualms in taking up one of Mac's bets to prove his prowess with the ladies by bedding an older woman of Mac's choice – Joanna. When Martin later discovers his half-brother's intentions he rushes over to stop it – which ends in a botox stabbing, staff on the run from the police in an ambulance and a major cliff-hanger – literally.