While in prison and preparing for parole after serving time for the murders of his mother and father-in-law, Mark met young probation officer Gemma. After his release, they develop a relationship and move in together. Although Mark feels that he is in control, Gemma is not as naive as he imagines; she's from a wealthy family and isn't committed to a lifetime career in the probation service. She begins to see him as a means to help her gain some revenge for the way her mother (mis)treated her father during his terminal illness.

After using Mark to help her achieve her aims, Gemma becomes increasingly bored with her situation and begins to separate herself from him. Mark won't let her go easily and won't let her get away with having used him to achieve her own ends. What ensues sees Mark returning to his previous sociopathic tendencies and extreme strategies.
This insightful and disturbing thriller culminates in a gripping climax set on the Adriatic coastline of Yugoslavia in the early 1980s.
Praise for Murderer: On Your Mark:
`Ian Marsh has used his experience to create a worthy academic crime novel, featuring a narrator who definitely doesn't put his students first. Murderer: On Your Mark is a wicked poison pill of a debut.' Paul Johnston, CWA Dagger Winner