Dr. Arthur Calgary, a geophysicist, arrives at the Argyle family's estate to tell them that their son, Jacko, who was convicted of murdering his mother, Rachel, is innocent. Calgary holds a crucial alibi that could have exonerated Jacko, who died in prison. The family, still reeling from the repercussions of Rachel's murder, is skeptical and resistant to reopening old wounds. Calgary is determined to clear Jacko's name and begins probing into the strained relationships and hidden secrets within the family.

As Calgary delves deeper into the lives of the Argyles, he uncovers motives, grudges, and potential suspects who all had reasons to want Rachel dead. His presence stirs up emotions and tensions among the family members, leading to confrontations and revelations. Each member's character and behavior come under scrutiny, revealing a web of lies and deceit. Calgary's investigation leads him closer to uncovering the truth, challenging the initial perception of Jacko's guilt and shedding light on the family's dark history.