Complex sentence: Spanner Films have released a press release saying they plan to produce a television drama series, "Undercovers", based on the story of the undercover police officers, written by Simon Beaufoy, Alice Nutter, and Franny Armstrong, and executive produced by Tony Garnett.
Split into simpler sentences: Spanner Films have released a press release saying they are planning a television drama series, "Undercovers", based on the story of the undercover police officers. They say the series is being written by Simon Beaufoy, Alice Nutter, and Franny Armstrong, produced by Spanner Films and executive produced by Tony Garnett.