Coronation Street's John Stape will hold his wife Fiz and four others hostage before he takes his own life.
The deranged teacher leaves Fiz (Jennie McAlpine), her brother Chesney Brown (Sam Aston), and friend Kirk Sutherland (Andrew Whyment) in fear of their lives when he imprisons them in the cellar of Alan (Michael McStay) and Dorothy Hoyle (Jean Fergusson), who he also holds captive as secrets about the three deaths he is involved in begin to unravel.
A source from the ITV1 soap told the Daily Mirror newspaper: "John's world starts to crash around him in spectacular fashion when all the terrible secrets he has been hiding start to piece together in one big jigsaw.
"It ends with all five people being locked in the cellar fearing for their lives as Stape mulls over how to get out of the biggest mess of his life. He finds himself in a situation where everyone knows what he has done. Suicide has to be his only way of escape. But will he take someone else's life?
"There are so many twists that each episode will be gripping."
John (Graeme Hawley) has been racked by guilt after watching friend Colin Fishwick - whose identity he had stolen so he could become a teacher again after spending time in jail for kidnapping Rosie Webster - die from a heart attack before burying his body in the foundations of the Underworld factory.
He then killed Charlotte Hoyle after she began blackmailing him over Colin's death before murdering Colin's mother Joy as she tried to track down her son.
When a disaster at Underworld sparks fresh building work, John - who has a three-month-old daughter, Hope, with Fiz - fears Colin's body will be exposed so decides to commit suicide.
Graeme said: "I can't see there being a happy ever after for John."