Nathan Maynard-Ellis, aged 30, disposed of the remains of Julia Rawson, 42, from Dudley, by hiding her body parts in plastic bags near a canal in Tipton last year, Coventry Crown Court was told.
Maynard-Ellis befriended Ms Rawson during a chance meeting at a micro-pub called the Bottle and Cork, in Dudley, on May 11, 2019, after she had got on the wrong bus, said Mr Karim Khalil QC, prosecuting.
The pair left the pub at 2am on May 12 - the last day she was seen alive - and went to Maynard-Ellis's home on Mission Drive, Tipton.
There, Ms Rawson entered a "flat of horrors" which contained stuffed creatures on walls, face masks, a Chucky doll, reptiles in tanks and DVDs about serial killers, Mr Khalil told jurors.
"She must have realised soon after she went in that she would not come out again. She must have panicked in there," he said.
"We, the prosecution, say all the evidence you will hear will provide an insight into the dark thoughts of Nathan Maynard-Ellis as he brought Julia home that night."
Maynard-Ellis's boyfriend, David Leesley, 25, was also in the flat that night and took part in Rawson's murder, the prosecution alleges.
Both men deny killing the former Dudley Market stallholder, who lived at Green Park Road in Kates Hill, Dudley, but they have pleaded guilty to concealing a corpse. Maynard-Ellis has also pleaded guilty to dismembering her body but Leesley denies this.
Mr Khalil added: "Maynard-Ellis wasn't acting alone. Everything that happened thereafter they [Maynard-Ellis and Leesley] did together."
Jurors were told that Maynard-Ellis suffered mental health problems for many years. He "harboured dark thoughts" about sexually assaulting and killing women and was interested in serial killers and the "dismemberment of bodies", said Mr Khalil.
Both defendants have also admitted perverting the course of justice.
Maynard-Ellis has further been charged with four counts of rape against a different victim, alongside one count of attempted rape and threats to kill.
The trial continues.