Jac and Joseph are operating in the theatre but it is boiling hot. Keith and the assistant nurse collapse and Jac and Joseph shout for help knowing that there is something wrong. Medics enter the theatre and take Keith and the assistant out on stretchers, leaving Joseph and Jac alone with the patient.
Jayne and an entourage of suited Trust lawyers sweep past Annalese and Michael on their way to an emergency meeting regarding the Hewitt case. Jayne explains that Kathy Hewitt won't stop until she has someone to blame.
The decision is made to cordon off the theatre as there might be something in the air causing the problem. Jac and Joseph carry on operating even though Joseph thinks that it might be carbon monoxide poisoning. He instructs Elliot to get the filtration system and extractor fan turned off in the theatre just in case. Joseph is in control but they need help as the patient is beginning to wake up. They need an anaesthetist and Marianna puts herself forward and heads into theatre.
Elliot tells Faye about the situation and she rushes to help Joseph. Faye tells Joseph that they still don't know what they are dealing with here but that they're working hard to get them all out. Separated by the glass, tears well up in Faye's eyes and we realise that they desperately love each other. They are interrupted by Jac who calls Joseph over. He looks at Faye and Jac, torn for a moment between the two women. Faye nods for him to go but Joseph doesn't move. He watches as Faye is led away by the security team. Joseph wants to save the patient and get out of quarantine so he and Faye can be a couple again.
Annalese's head starts to spin - as soon as the breathalyser test results are known, the fake post-operation notes will come to light and it will be revealed that she killed Hewitt. Annalese stops in her tracks realising that she can't go back to work and pretend that nothing has happened. Michael takes Annalese aside and says that they must carry on putting up a united front. They need to be strong for each other and get through this. Donna walks past and Annalese throws her a sharp look, Donna quickly leaves them.
Elliot tells Joseph that the filtration system has been turned off but Joseph and Jac are still feeling the effects of the problem so it can't be carbon monoxide. Elliot calls everyone together so that they can discuss what they're going to do. He tells Jayne that he believes it is the patient causing the problem and that they should get them out of there as soon as possible. Jayne doesn't want to do anything yet as it could risk more contamination.
The situation is gradually getting worse in theatre. Marianna is feeling the effects but insists she is fine. Elliot suggests they evacuate Holby but Jayne feels that they should wait.
On the ward, a frantic Faye is trying to maintain control - all she wants to do is get back to Joseph but people are asking questions about why they can't leave. In theatre the ventilation is switched off and Joseph and crew stay with the patient as they have a duty of care.
Meanwhile, the patient's son arrives. Elliot is desperate to find out more information about the patient and Elliot explains that his father was involved in a serious road accident. However his son says that he has no idea what he was carrying even though Elliot doesn't believe him.
Jac, Joseph and Marianna are still in theatre as the operation is taking longer than expected. They want to get out but have to wait for the decontamination team. Marianna is starting to feel the effects and collapses. She needs help but they can't leave the room. Jac gives Marianna some assistance but needs to get out fast.
News has now spread about the lockdown in the operating theatre. Faye is obviously upset and Linden comforts her. We can see that he is hiding feelings for her. Faye doesn't know what she'll do if she loses Joseph now.
Meanwhile Daisha decides that it is the perfect time for a holiday but Mark doesn't think she should go alone.
Jac and Joseph try to help Marianna but it's too late and she dies. Jac breaks down as she realises that this is something serious, they might die in here. Joseph and Jac are starting to feel ill and they rest on the floor of theatre. In silence the two realise that it's only a matter of time before they go the same way as Marianna. Jac takes hold of Joseph's hand and breaks the silence by telling him that she still cares for him. They share a moment retelling stories of when they were happy together and Jac is touched by Joseph's kindness towards her. Jac regrets the past as she'll never be able to unpick it and has lost the only man she's ever truly loved.
A nervous Donna finds Annalese. She is nervous as this is the first time that she's had to face her since she found out about her fling with Michael. Donna apologises, but Annalese doesn't want to hear it. Annalese explains that it was just sex as he doesn't love Donna and never will.
Mark tries to convince Daisha that a holiday might not be the best idea but Daisha tells him that she wants him to leave her alone. She can't do anything without him interfering. Daisha leaves when her sister Lalaine arrives out of the blue.
The patient's son hears that Marianna has died and knowing that the police will now get involved tells Elliot that he believes his father was carrying chemical pesticides. Elliot now knows what they are up against and can try to help save Jac and Joseph.
The decontamination team finally arrive but Joseph's condition has deteriorated. Jac jumps into action as she is not going to lose Joseph now. She screams down the phone for help and she clearly still loves him. The team arrive just in time but Joseph doesn't look like he'll make it. Faye rushes to Joseph as he is taken out to be treated and waits with him until he wakes up. When he comes round he sees Faye staring at him and they embrace. It's clear that Joseph and Faye are meant to be together.
Tagged in Holby City