Feisty ward sister Chrissie returns to Holby (BBC1, Tuesday) and something’s troubling her. But she’s not in a hurry to reunite with Sacha, as actress Tina Hobley reveals…

How were things between Chrissie and Sacha before she went off to Australia?

“They were not in a good place – Chrissie was terribly upset about the fact he’d not told her about Daniel’s hole in the heart. Chrissie felt really let down by Sacha. The one thing she thought she could do was trust him and he broke that trust. She needed some time alone.”

What brings Chrissie back to Holby a week earlier than planned?

“She’s found a lump in her breast and, with her family history and recent scare, she’s very concerned.”

Why does she go to Michael Spence with her worries rather than Sacha?

“Michael is Chrissie’s knight in shining armour – he’s the one who can sort things out without any fuss, whereas Sacha brings confusion. The fact Chrissie goes to Michael and not her husband highlights that things are not right in their marriage.”

And when Chrissie and Sacha are eventually reunited, she lies about why she’s come back, doesn’t she?

“That’s right. She says she’s there because a friend is sick and she’s referred them to Michael. The way Chrissie covers things up with this ‘friend’ is quite moving actually as Chrissie herself in a really scary place and she’s terrified. She feels unsure, scared and very alone.”

While Michael’s giving Chrissie her prognosis, Mo tells Sacha about seeing Chrissie with Michael before she went to Oz. Why does Sacha immediately think the worst?

“Well, because Chrissie has spent a night with Michael. They weren’t ‘together’ together but, the morning after, there is a natural intimacy that Mo sees; that naturally chemistry between two people. The fact is, Chrissie’s now at a point where she really needs her soulmate and her partner – and it’s not Sacha.”

Having grown suspicious of Michael and Chrissie’s closeness, Sacha drops the bombshell that he wants a separation. How does Chrissie react?

“People have been expecting Chrissie to be the one to hurt Sacha, so there’s almost a sense of relief that this has come from him, so she’s not seen as the bad guy. But she knows a separation is right for them.”