2. DO WE KNOW WHAT’S CAUSING THE BLACKOUTS YET?

Marcella’s blackouts, or fugue states, are a psychiatric disorder. When they strike, she temporarily loses control of her actions and seems not to remember anything afterwards.

In series one, she shoved estranged hubby Jason down the stairs, buried a body in the woods and nearly suffocated a man to death.

That’s some pretty intense sleepwalking. But we don’t need a medical degree to figure out when the blackouts happen – they occur at times of high stress or trauma.

Jason had just told her he didn’t love her any more. And in the series two opener, Marcella thought her 12-year-old son Edward had been abducted. She flipped, as anyone would. Except in her case it involved nasty violence.

Not only did she drag Jason’s new fiancée, Becky, out of her car and throw her up against the bonnet, she also gave a fellow school mum a resounding whack across the head.

You can bet that the next time Marcella gets bad news, it won’t go well.