In Le Crime est notre affaire the 2008 French adaptation by Pascal Thomas of 4.50 from Paddington, Alexie Charpentier is a teenage girl who is the parallel of Alexander Eastley in the original novel. The only difference is that she is descended from Roderick Charpentier through her father Frédéric Charpentier whereas Alexander is descended through his mother Edith Eastley née Crackenthorpe. Alexie is portrayed by Alexie Ribes.
Alexie plays largely the same role in the plot as Alexander in the original. Among other things she fills in Prudence with background information about the members of the family. Later, she and her friend Valerie show Prudence the location of "the museum", a run down building in the chateau grounds where Roderick Charpentier keeps his collection of antiques and archaeological artefacts.
Like the children in the original novel, Alexie and Valerie hunt for clues when the dead body of a woman is found on the chateau grounds. Thus they find a letter from a certain "Martina".