In the novel They do it with Mirrors Alexis "Alex" Restarick was the older brother of Stephen Restarick. He was Johnnie Restarick's son from his first marriage, and was Carrie Louise Serrocold's stepson. He viewed Carrie Louise affectionately, as if she was his own mother, and addressed her as Madonna. He loved Gina and also worked in the theatre.
Alex was described as "sleek", a "handsome young man, and one who bore on him the authority and good humour of success".
He arrived at Stonygates just after Christian Gulbrandsen was found murdered, and became a suspect because he had taken longer than he should have to drive from the lodge to the house. He explained that he had stopped to study the effect created by the fog and the headlights, as well as the sounds of shots and running footsteps that he heard. He was considering what he could use to get the same effects in a ballet he was producing, Limehouse Nights.
The day after the murder, Carrie Louise received a box of chocolates by post. A card with Alex's name was inside. However, he said that he had not sent any chocolates. The chocolates were later found to have been tampered with, and six chocolates with Kirsch flavouring (Carrie Louise's favourite) contained aconitine.
Alex gave Carrie Louise an unusual pair of scissors, with two finger holes on one side, and one on the other. They were supposed to make it easier to cut the fingernails on the right hand. He asked her to try it there and then, and cleared the nail clippings away. Miss Marple later said that he did this because he had guessed that the supposed poisoning of Carrie Louise was only a ruse, and an analysis of her nail clippings would show whether arsenic had actually been administered over a long period of time.
As part of his investigations, Inspector Curry had Constable Dodgett run from where Alex said he had been standing on the night of the murder, to the house. This was to see how long it would have taken for Alex to run to the house, shoot Christian Gulbrandsen, return to the car, and make his entrance in the Great Hall.
Inspector Curry also remarked that a stage set creates an illusion for the audience, but is itself real, being made of real materials. This gave Alex the idea of looking at the Great Hall as a stage set, an idea which he shared with Miss Marple. He also told her about Constable Dodgett running to the house, and how he was puffing and panting when he came back. These ideas help Miss Marple deduce how the murder was committed.
Alex was in love with Gina, and asked her if she was going to marry him, or his brother Stephen. He told her that Stephen was better looking and very intense, but with him, she would find life entertaining. He kissed Gina, and Mildred Strete caught them.
Alex was later found dead in the theatre, together with Ernie Gregg. The big counterweight had fallen on them.
Murder with Mirrors (1985)
In Murder with Mirrors (1985), Alexis Restarick is not featured. Miss Marple is the one at the receiving end of a falling row of theatre lights.
BBC's Miss Marple
In the BBC 1991 adaptation of the novel which formed part of the Miss Marple series, his name is slightly altered to "Alex Restarick". He is played by Christopher Villiers. Like in the book, he is injured in the theatre together with Ernie. Ernie dies but Alex is sent to the hospital and survives.
ITV's Agatha Christie's Marple
In the ITV 2009 adaptation of the novel as part of their Agatha Christie's Marple series, Alexis Restarick is not featured. Instead his father Johnnie Restarick makes an appearance just as the murder is believed to have taken place, making him also a suspect.