The Stranger in Her House by John Marrs

The plot of this thriller revolves around Connie's suspicions about Paul, a stranger who enters her family's life under the guise of helping her elderly mother, Gwen. Here’s a summary:

Paul presents himself as a helper sent by a charity to assist Gwen, an elderly widow. Initially, his kindness and involvement set off alarm bells for Connie, Gwen's daughter. Connie is protective of her role in caring for Gwen and feels increasingly uneasy as Gwen becomes more reliant on Paul.

Despite Connie's concerns, Gwen seems to trust Paul completely, which fuels Connie's suspicions further. As Paul's visits become more frequent and he eventually moves into Gwen's home due to circumstances, Connie becomes convinced that he is manipulating Gwen and trying to push her out of her mother's life.

Connie's attempts to expose Paul intensify as she battles to regain control over her family dynamics. However, her escalating actions lead others to question her grasp on reality. As events spiral out of control, Connie faces a critical decision: should she confront Paul directly, risking Gwen's trust and potentially losing her forever? Or is this exactly what Paul has been orchestrating all along—to isolate Gwen and undermine Connie?

The story promises to be a suspenseful exploration of trust, manipulation, and the lengths one will go to protect family, wrapped in a psychological thriller that keeps readers guessing until the very end.