It’s a dramatic week for Holby fans as tonight sees the first of a special two-parter that concludes on Thursday.

We begin with Jac handing in her resignation, then go back in time 10 hours to work out why.

The usually unemotional surgeon is terrified of a big operation she has to perform – her hand is shaking and her nerves are shot. What has happened to Holby’s ice queen?

There’s also a new face on the wards, Professor John Gaskell, played by Paul McGann, who comes with a reputation for achieving what was thought to be impossible.

But as medical history is made, lives saved and new beginnings created, there’s also a terrible darkness about to engulf the hospital…

This show airs at 10.45pm in Scotland.