The Alibi Man - S1.E17

Based on storyline in Gideon's March. Famous racing driver Jack Hedley has been fiddling the books and is caught by his accountant Geoffrey Palmer, who he kills to keep him quiet. Mechanic James Culliford gives him an alibi because he owes his life to him. Gideon investigates and Hedley's mistress needs to die too. A rare case where the murderer gets away with it.