Neighbours returnee Scott McGregor has admitted that filming Mark Brennan's shock comeback scenes was a challenge.
Mark was thought to have died in witness protection nearly two years ago, but a new storyline will see his ex-girlfriend Kate Ramsay (Ashleigh Brewer) left shell-shocked when he reappears in Erinsborough.
Kate is watching an eclipse with new boyfriend Mason Turner (Taylor Glockner) when she catches her first glimpse of Mark.
The shocking sight interrupts an important moment for the new couple, as Mason has just declared his love for Kate.
McGregor told TV Week: "She's at the park with Mason and as the eclipse happens, she sees what she thinks is a glimpse of Mark. But she doesn't know whether or not she's dreaming.
"She can't believe what she is seeing and doesn't know what to think. It kind of takes her breath away, because no-one would know how to react to that."
The actor continued: "I missed Ash and it was amazing to be able to share the screen with her. We spoke a lot about getting the scene right, because there's not many people in the world that have experienced something like that. It's a hard head space to tap into, but it came out really well."
With Mark disappearing as soon as the eclipse is over, Kate tries to find an explanation for what she has seen.
When Kate asks Toadie Rebecchi (Ryan Moloney) for help, he does some digging and discovers that Wes Holland - the main threat to Brennan's life - has recently been killed.
McGregor added: "What you learn is that Wes, the threat to Brennan's life, had tracked him down when he was in witness protection. There was a scuffle and all you really know is that Brennan came out on top. He won the fight and lived to tell the tale."
Brennan is expected to be back on screen for a month.