Notorious criminal Beryl "the Beefcake" Bagshot, now 85, escapes from prison and is believed to be putting her former gang back together ready for an audacious heist. Her plan is to steal the 'Invigatron': a device that fires beams of healing energy and can repair injuries.The one person Beryl still needs to find is Harry "Fingers" Fulson, now retired from crime and working as a handyman.
Meanwhile, St Hope's are holding a school disco and everyone is expected to bring a partner. Carrie invites Donovan, thinking nothing of it, but her ego is bruised when he simply laughs at her. The spies devise a plan to pretend that Frank's leg is broken, and thereby bring Harry to St Hope's as a replacement handyman. Eventually Beryl calls Harry and persuades him to meet her at a nearby retirement home, now the nerve centre of her criminal empire. She persuades Harry to join the gang and outlines her plan to steal the Invigatron.
Harry is ordered to steal the chemical ingredients for a knock out gas vital to the plan from St Hope's. Once there he is followed by Chloe as he collects various items from around the school and he tells her how he wanted to be a dancer when he was younger, but instead made a choice that affected his whole life. Just as the two start to bond, Harry rushes off and Carrie is ushered away by Mrs King.
When Carrie finally gets to HQ, Rose realises what the ingredients Harry collected are designed to make and they figure out Beryl's plan. The spies rush to intercept the heist but are outwitted by Beryl's gang and eventually captured. With Beryl set on destruction and the spies unable to stop her, will Harry's allegiance to Beryl outweigh his friendship with Carrie, or will he come to the rescue?