The murderer, played by Graeme Hawley, will apparently go on the run after wife Fiz (Jennie McAlpine) finds him holding her brother Chesney and Charlotte Hoyle's parents Alan and Dorothy hostage.
However, as a police man hunt gets underway, John hides in a tiny loft in his house to avoid arrest - similar to the real-life case of John Darwin, who hid next to his house in Hartlepool after faking his own death in an insurance scam.
According to The Sun, viewers will see John sneak downstairs at night for food and to watch Fiz and daughter Hope sleep. When Fiz catches him holding Hope, he flees with the baby.
Fiz is knocked down as she tries to rescue Hope. John visits her in hospital and Fiz hits a panic alarm, resulting in him running onto the roof. He will allegedly threaten to jump with Hope.
A source said: "John truly believes he's a good man who had bad luck. He's lost the plot."
Previous reports have suggested that John will commit suicide.