The HBO series 'IT: Welcome to Derry' serves as a chilling prequel to the acclaimed films 'IT' and 'IT Chapter Two', delving deep into the sinister origins of the entity that plagues the seemingly quaint town of Derry. Set in 1962, the show meticulously crafts a narrative where no one is safe from the relentless cycle of fear and terror, forcing its characters to confront the unsettling question of whether what they perceive is real or merely the illusion of a malevolent shape-shifter.

Central to the series are a new group of 'Losers', including Lilly (Clara Stack), Will (Blake Cameron James), Rich (Arian S. Cartaya), Ronnie (Amanda Christine), and Marge (Matilda Lawler). Despite encountering Pennywise the Dancing Clown in the sewers, Lilly remains determined to wield a specially formed dagger against the entity, a resolve not shared by her companions. As both children and adults grapple with their deepest traumas, they discover that the entity is not the sole evil lurking within Derry.

A significant aspect of the production involved maintaining the authenticity of the young cast's reactions to Pennywise. Bill Skarsgård, who portrays Pennywise, was intentionally kept isolated from the actors until their actual filming of scenes together, particularly the pivotal sewer encounter. This approach ensured that the terror displayed by the cast was genuine. Matilda Lawler described the experience of seeing Skarsgård in full Pennywise costume as an "entirely unique experience" and "terror," emphasizing the imposing presence and the combined effect of costume, makeup, prosthetics, and Skarsgård's intense energy. Clara Stack and Amanda Christine echoed these sentiments, confirming that their on-screen reactions were their real, unfeigned responses to encountering Pennywise for the first time.

The series features several gruesome and emotionally intense set pieces that challenged the actors. The movie theater attack sequence, a highlight of the first episode, was particularly demanding. Amanda Christine, whose character Ronnie is an observer in the scene, found learning about film camera operation and being part of such a significant early sequence "really fun." Clara Stack recalled the thrill of blending performance and intense emotion with complex blocking, navigating an action-packed scene while being drenched in fake blood and screaming. The sight of Lilly holding Susie's ripped hand in the theater lobby, a shocking moment, was memorable for its impactful horror.

Matilda Lawler discussed the harrowing sequence in episode four where Marge attempts to harm her own eyes. Describing it as "trippy" and emotionally draining, Lawler expressed deep sympathy for Marge. Filming involved reacting to tiny wires for CGI effects, a challenge that required immense physicality and emotional commitment. Lawler credited her acting coach and the supportive environment, including encouraging high-fives from fellow young cast members, for helping her through the horrific scene.

Amanda Christine recounted the "gross" experience of filming Ronnie's birthing moment, where her character drowns in sheets and is birthed from her mother. This involved being constantly covered in sticky goo and white baby-like fluid for days, along with water training to simulate being in the womb. Despite the discomfort, Christine found the overall experience "really, really fun," thanks to the direction of Andy Muschietti.

The co-stars promised a season full of shocking moments and plot twists. Clara Stack anticipates audiences will be "really terrified and really shocked" by the numerous surprises and horrific sequences. Matilda Lawler and Amanda Christine highlighted that the later episodes delve even deeper into the entity's origins, drawing stronger connections to both the original 'IT' novels and the previous films. 'IT: Welcome to Derry' airs on HBO and is available to stream on HBO Max, promising a terrifying and revealing journey into the heart of Derry's evil.