Who does he play? Philip Marston is a billionaire businessman. He's arrived on Saint Marie to get married at one of the luxury hotels he owns – but his wedding day turns into a tragedy when his fiancée apparently takes her own life in a dramatic plunge from a balcony. Philip is furious when DI Jack Mooney insists this is a murder case.

Where have I seen him before? Veteran TV actor Denis Lawson has a CV as long as your arm. Recently he has been in Victoria, playing the Duke of Atholl who welcomed the Queen to Scotland. In the ITV drama In Plain Sight he played Laurence Dowdell, and in New Tricks he starred as Steve McAndrew.

Pearl Marston – Tanya Reynolds

Who does she play? Pearl Marston is one of the three Marston siblings. Having lost her mother 15 years ago to cancer, she has her wealthy dad wrapped around her little finger - but she is "totes" not a big fan of her soon-to-be stepmother. Pearl definitely doesn't want a real job: she prefers a life of pilates classes, massages and social media.

Where have I seen her before? Tanya Reynolds has appeared in the TV series Delicious, where she played Teresa Benelli. She also popped up in Rellik as Sally, and played Lady Isobel Dunsany in an episode of Outlander.

Karen Marston – Jemima Rooper

Who does she play? Karen may be young, but she is the only Marston kid to inherit her father's business sense. She is the Managing Director of the Marston Group and, in her own words, has dragged the business into the 21st century.

Where have I seen her before? Jemima Rooper started young, playing tomboy George in The Famous Five. More recently she's starred in Fearless (as Maggie Berman) and Atlantis (as Medusa).

Stephen Marston – Rob Heaps

Who does he play? Stephen lives a life of luxury. His position in the family business enables him to travel the world doing "quality control" at the Marston hotels and flirting with everyone he meets.

Where have I seen him before? Home Fires fans will remember Rob Heaps as AC Tom Halliwell. More recently he played Ezra Bloom in the TV series Imposters.

Oliver – Stefano Braschi

Who does he play? Oliver manages the Marston hotel in Saint Marie, where the wedding was due to take place and where the "suicide" happened. He is officious and uncooperative with the police.

Where have I seen him before? Stefano Braschi played Marco D'Oliveira in Waterloo Road. He's set to appear in the movie Genesis as Vice President Jimenez, and will play Jason Walker in Hard Sun.