It's the day of the hospital Christmas party, a posh ticket-only bash at a hotel across town. However, this being Holby, disaster isn't far around the corner, and sure enough, on their way to the bash the medics soon find themselves in the middle of a huge traffic pile-up which traps them all inside a packed, claustrophobic tunnel. Luckily, the team are virtually uninjured and set about helping the other passengers - including a drastically unwell teenage girl - while outside the tunnel, Selena is first there and forced to cope single-handedly until the emergency services arrive.

At the heart of the accident scene, Donna begins raiding cars to find equipment to treat the injured, while Kelsey is overcome by her fear of the dark - and no amount of consoling from Woody seems to help. But an attempt to save a baby soon threatens the lives of all those who are trapped.