Carrie Louise Serrocold (née Martin) is the sister of Ruth Van Rydock and a long time friend of Jane Marple. She lives at Stonygates, which she has turned into a school for juvenile delinquents, together with her husband, Lewis Serrocold.
She has been married three times. Her first husband was Eric Gulbrandsen, who died when Carrie Louise was 32. Her second husband was Johnnie Restarick. He died soon after their divorce. Carrie Louise's third and currant husband is Lewis Serrocold. She has two daughters, "Pippa" (who was adopted) and Mildred. Also she has three stepsons from both her first and second marriages Christian Gulbrandsen, Alexis and Steven Restarick.
At the beginning Jane comes because her sister Ruth is concerned for her, Jane is welcomed by her and the family. Carrie Louise is clearly weaker than she use to be and clearly is childlike in mind. After dinner Edgar Lawson confronts Lewis about his parentage Lewis speaks to him in his study. While this goes on Carrie convinces everyone that Edgar is harmless and Lewis treats him like a son, just then two shots fill the air but both men are fine but soon after Christian is found dead. Later on Carrie received a box of chocolates from Alexis but he admits he didn't send, afterwards it's tested and it's revealed to Carrie that someone has tired to poison her which she can't believe to be true. She is a witness to Miss Marple's reveal that Lewis has been stealing from the trust, which was why Christian came to tell her and that the poisoning was false proven by Alexis who had nail cuttings tested. However she watches in horror as Edgar (who was in on it) runs away, with Lewis and police in chase as they drown in the lake. While upset Carrie is reassured that Lewis tried to do good, however Jane reassures her that it was her simple mind that helped the case to be solved.
- She was played by Bette Davis in the movie Murder with Mirrors. This version is quite faithful in it's retelling of Carrie, the biggest change is that Miss Marple asks for nail clippings herself.
- She was played by Jean Simmons in the 1991 BBC version. In this version, Miss Marple is not her school mate but a kind of "governess companion" who accompanied Carrie Louise and her sister on a grand tor of Europe in their youth. It's revealed after Lewis' death that the Gulbrandsen Trust Fund which supported Stoneygates had been bankrupted through Lew Serrocold's embezzlement. However Lewis had been unable to touch Carrie Louise's own personal money and so she could continue live the rest of her life in comfort.
- She was played by Ursula Howells in the 2001 BBC Radio version.
- She was played by Penelope Wilton in the 2009 ITV version. This version has some changes to Carrie Louise's character. She is portrayed as being much more concerned and involved in the management of the Stoneygates reform institution. She presides at lunches for all the boys, and takes Miss Marple around and introduces the inmates to her. The amateur theatricals is also her idea rather than that of Lewis. Her ex-husband Johnnie Restarick is still alive and comes to Stoneygates. Carrie Louise confronts Mildred over her jealousy of Gina. Carrie Louise sells Stonygates at the end of the show.
- In Jeux de glaces, the TV film adaptation of Agatha Christie's They do it with Mirrors by France Télévisions, the parallel character is named "Rose-Marie Bousquet". Here, Etienne Bousquet is her second husband and not her third. She has one natural daughter from her first marriage, Jacqueline Cassard and has another adopted daughter Juliette. In the dialogue she seems to imply she had another daughter as she refers to "the other Juliette". Like in the 2009 ITV version, she is active in supporting her husband in running the rehad centre and loves him for his devotion. The only difference is that here she is complicit in her husband's crimes. Etienne confesses that he is in trouble and that Pierre Montauban would shortly expose his embezzlement. Rose-Marie, out of love for him, and despite the fact that he is embezzling her own money, helps him out by planning the killing. After Etienne is arrested, she tries to commit suicide but Commissaire Laurence arrives in time to stop her and put her under arrest. The character of Rose-Marie is played by Catherine Mouchet.