"High Tide" is the 988th episode of Casualty and the 27th episode of the 30th series. It was preceded by "Fatal Error - Part Two" and followed by "Sweet Child of Mine". The episode was directed by Julie Edwards and written by Kelly Jones.
It features the first appearance of paramedic Jez Andrews, portrayed by Lloyd Everitt, who departed the show almost 18 months later. It also marks the final appearance of staff nurse Ben "Lofty" Chiltern, portrayed by Lee Mead, after just over two years on the show. Mead later reprised his role as Lofty on Holby City in 2017.
Emilie is due to be moved to a different location away from the hospital before she dies. Cal and Ethan accompany her in the ambulance with Iain and his new paramedic partner Jez. Meanwhile, Lofty's hearing date arrives but he is left feeling nervous, and Connie and Jacob take their day off to spend time together. Diane's teenage daughter Lana arrives in the ED drunk, and it soon transpires that she knows that Lofty was responsible for her mother's death.
Whilst on the road, Emilie once again reminds Cal and Ethan of her wish to go back to Conleth Bay whilst looking at old photographs. They trick Iain and Jez into getting out of the ambulance only for Cal to go into the front and drive off leaving the paramedics stranded. Shortly after they arrive at a tourist café located near the beach and get directions from a waitress there who also gives Ethan her number. Emilie chokes on a sweet and Cal has to resuscitate her, and they continue their journey. Back in the ED, it's clear that Lana is suffering with mental issues and despite her grandmother's attempts to get her to see a psychiatrist, she says she won't go. Iain and Jez continue their walk along the lane in the hope of getting someone to stop and give them a ride back to the ED.
Lofty misses his hearing with Michael Hall and other senior staff when he prioritises Lana's treatment. He climbs into the vent after realising she has climbed up, and encourages her to get treatment. She expresses her regret for telling her mother she hated her, and that she will never be able to take it back. Meanwhile, Ethan accidentally stumbles upon Cal's letter from the genetics lab whilst looking for medication for Emilie. Whilst distracted, Cal accidentally steers off the road into the bushes at the side. Things are made worse when a police officer becomes suspious whilst driving past, but Ethan is able to trick her by dressing up in a paramedic uniform in the back of the ambulance. They get the ambulance started again and set off for the bay. Jez ends up giving Iain a piggyback after a speeding car results in Iain jumping backwards out of the road and he twists his ankle. They are eventually given a lift by a group of women in a car driving past.
After Rita informs Lofty that he could still keep his job with some training, he tells her that he is going to leave in order to partake in a charity hike and have a break from work. Meanwhile Cal, Ethan and Emilie arrive at Conleth Bay. Cal and Ethan run around on the beach having fun whilst Emilie overlooks in joy from the ambulance. They manage to get her out of the ambulance and onto a bench, at which point they decide to open their letters. Ethan didn't think he had one as he had never sent off, but Cal reminded him about when he demonstrated an injection back in January, and he tells him he send the blood he collected off instead of getting rid of it. Cal opens his and it comes back negative to him and Emilie's relief. Ethan opens his and tells Cal and Emilie his is negative too. Shortly after, Emilie dies. Ethan then reveals that his test was positive, meaning he has inherited Huntington's but lied to make Emilie happy.
At the ambulance station after safely getting back, Iain tricks Jez into thinking that his mother will be coming to tell him off for his unprofessional manner during the shift, which scares him as he was telling Iain how scary he finds his mum. Outside Lofty says goodbye to his colleagues and leaves the department for now.
This episode used various other locations for main filming locations in the episode. Scenes set at Conleth Bay were filmed in Porthcawl, South Wales whilst scenes on the roads were filmed in and around the Cardiff and South Wales area.
The episode saw the departure of Ben "Lofty" Chiltern following his arrival on the show in March 2014 during series 28. The character's final appearance was expected by many fans due to circulating rumours in the weeks leading up to the episode. Lee Mead has made it clear that it will most likely not be the last time Lofty is seen on the show, and his return has been hinted.
This episode also saw the arrival of new paramedic Jez Andrews. The character, portrayed by Lloyd Everitt, is a replacement paramedic for Kathleen "Dixie" Dixon whose departure scenes aired at the end of January 2016. The character's arrival was first announced in January 2016 shortly before Dixie's departure.
Following the episode's broadcast, a spring trailer was posted by the BBC online featuring scenes with Elle Gardner and David Hide. This coincided with a week's break before the next episode aired on 26 March.
Comments from fans over BBC Casualty's social media pages indicated overall praise for the episode. The emotional scenes between Cal and Ethan were said to have gone well with Lofty's departure, and a comedic element was added through Jez and Iain's roadside escapade. Some further went on to label it the best episode, whilst others were angry at the fact Ethan discovered that he had Huntington's.
Many fans noted that Lofty's departure was less significant due to the importance of Cal and Ethan's storyline. The episode was also Ethan centric. Furthermore, by the time the episode aired most fans were aware that Lofty's departure would only be temporary and therefore were less touched by him leaving. Some fans expressed annoyance at Lofty's exit storyline being too rushed, something which series producer Erika Hossington had previously noted about Ash and Tess' departures.