According to DenofGeek, Playdate will have 5 episodes:

Alex Dahl’s bestselling thriller novel Playdate is being adapted into a twisty five-part series for Disney+. It centres on every parents’ worst nightmare: mum Elisa lets her daughter Lucia go on a sleepover at a new friend’s house, but when she goes to collect her the next day, she discovers the house was a holiday rental and discovers Lucia, her friend Josie and Josie’s mother have vanished. In the urgent manhunt that follows, Elisa and her husband Fred find themselves under public scrutiny, and secrets about their past come to light, which explain the reason Lucia was taken. The cast includes  Denise Gough (Andor), Holliday Grainger  (The Capture), Ambika Mod (This Is Going to Hurt), Jim Sturgess (Cloud Atlas) and The Suspect’s Bronagh Waugh.