A lead actor can make or break a TV show. And Agent Carter struck gold with Hayley Atwell, she brings a vibrant spark of personality that lifts the entire series. What was originally commissioned to plug a gap when Marvel's Agents of SHIELD went on a midseason break fizzes with a retro zing that brings to mind the cinematic adventure serials of the 50s with a modern twist.

The post-World War II setting also gives Agent Carter its own distinct personality amongst the myriad Marvel Cinematic Universe productions. Season two sees Peggy Carter relocate to California to investigate a body found frozen in a lake in the middle of the sweltering LA summer. Of course this murder is just the tip of the iceberg of a whole new conspiracy.

Marvel are experts in building fictional worlds and Agent Carter cleverly exploits its links to the wider MCU (Atwell made her Marvel debut as Steve Roger's love interest in Captain America: The First Avenger). And if Marvel want to continue to expand their reach it's exactly the kind of show that could hook in a new audience. The first few episodes of season one were like a breath of fresh air. They made a virtue of Atwell playing the first female character to top line a Marvel production. The inherent sexism she faced in the workplace, constantly undervalued and underappreciated by her boss, was a core component. However it squandered much of its early promise and settled into coasting on formulaic plot devices.

Season two's switch to California promises a hint of Hollywood glamour but, in episode one at least, it appears to be just a sunny backdrop to a very similar storyline. The tentative romance with Daniel Sousa (Enver Gjokaj) is still simmering away while Edwin Jarvis (James D'Arcy) continues to provide the buttoned up fish out of water comic relief. Agent Carter is fun and sparky but it needs to grow and move forward rather than simply relying on the effortless charisma of its leading star.

Marvel's Agent Carter season 2 premieres on FOX, Thu 28 Jan, 9pm.