The jury in the trial of a mother accused of murdering her two young children has been told to avoid thinking her actions were simply "mad".
Fiona Donnison, 45, of Lightwater, Surrey, denies the murder of Harry, aged three, and two-year-old Elise.
Their bodies were found in holdalls in the boot of Ms Donnison's car near the former family home in East Sussex.
Christine Laing QC, prosecuting, told Lewes Crown Court there was a level of planning involved in the killings.
In her closing speech Ms Laing added: "There is something about a mother killing her own children that leads people to instinctively think that she must be mad.
"We know from evidence that killing two children in this way would have taken many seconds, possibly tens of seconds to kill them."
She told the juror Ms Donnison then put the children into separate bags and drove from her rented property in Lightwater to her former home in Heathfield, East Sussex.
Ms Laing said: "It well and truly puts paid to the notion that the killings were as a result of cognitive malfunction.
"There is nothing loving about the effort it took to contort Harry's body, bending his legs underneath him to put him into that bag."
Lewes Crown Court was previously told Ms Donnison walked into Heathfield police station in a distressed state on 27 January last year and told police she had killed the children.
The prosecution alleges she murdered them to hurt their father, Paul Donnison, 48, following the breakdown of their relationship.
Ms Laing told the court she switched the sat-nav in her car off so her journey could not be traced and then turned her phone off "because she was lying in wait" for someone.
"Fiona Donnison probably thought it was a safe bet he would return but of course he didn't and, whatever the final part of her twisted plan, to kill him or to blame him for the killings, it failed for the simple reason that he had stayed with [his new girlfriend] Ms Shimmens," Ms Laing said.
Jurors have heard claims she was suffering from depression and was not in her right mind at the time.
Former city worker Ms Donnison was not married to her partner and changed her name to his by deed poll.
The trial continues.