In the summer of 1997, the Tanner family moved into 52 Cavendish Avenue. They were what estate agents would call "ideal buyers": dual academic salaries, three beautiful children, and a golden retriever named Bixby.

David Tanner was a virologist at Addenbrooke's. His wife, Eleanor, taught piano. Their eldest son, Simon, was just about to turn 15 when they moved in. Neighbours remembered him as "quiet, but polite." Their two younger children — Holly (12) and baby Leah (7) — were often seen playing under the apple trees in the back garden.

But within nine months of moving in, they were all dead.

March 20, 1998. One of those rare nights in Cambridge when the clouds won't clear and the air feels soaked with something older than weather.

At 3:04 a.m., emergency services received a call. A single, breathless voice.

The dispatcher asked for clarification. The boy on the other end just said:

When police arrived minutes later, they found the front door unlocked. The house was silent.

Inside was something else entirely.

David Tanner was found in the home studio, slumped in his desk chair, a soldering iron embedded in his neck.

David Tanner's home studio - where the first victim was discovered

Eleanor lay in the downstairs annex bedroom, her skull fractured in three places. The room smelled of bleach and lavender oil.

The downstairs annex - scene of the second murder

Holly was discovered in the garden room, face down, her hands folded over her chest. A child's recorder lay next to her.

Leah, the youngest, was still in her bed. No visible trauma. An empty vial of sleeping pills on the floor.

Leah's bedroom - the youngest victim showed no signs of trauma

Simon Tanner was found sitting cross-legged on the decked terrace, facing the pond.

He was covered in blood. But not his.

Simon had kept a journal — hundreds of pages, scrawled in mirrored handwriting. The last entries were drawings: pond frogs flayed open, diagrams of stars and "garden gates," and a line repeated over and over:

Simon's journal - hundreds of pages of mirrored handwriting and disturbing diagrams

Police initially suspected mental illness. But forensic linguists noted that some of the symbols and phrases matched fragments of proto-Celtic ritual texts — eerily similar to those found in local university archives.

The courtroom where Simon Tanner's case was heard

He was found unfit to stand trial. Committed to a secure psychiatric facility under a sealed name.

He hasn't spoken a word since.

The Tanners' extended family sold the property in 2002. A series of owners have come and gone. The garden has been re-landscaped. The annex remodeled. The original pond was filled with gravel — yet moss keeps regrowing in a perfect circle where it once was.

The house today - remodeled but unable to escape its past

Tenants have reported:

• Hearing a recorder playing softly at night from the garden.
• A wet patch appearing in the upstairs hallway during full moons, though no pipes run nearby.
• Lights flickering in the home studio when no one's inside.
• Cats refusing to cross the threshold.

The windows where lights are sometimes seen flickering when the house is empty

In 2016, a family left in the middle of the night and never returned for their belongings. They broke the lease and refused to speak to reporters. One anonymous quote in The Cambridge Independent read: