American software boss Clinton Finn becomes the fifth victim of the mysterious "Bucketman" of Midsomer when he and his luxury car are doused in paint and glue.


The Midsomer Cycling Club is training for the Pilgrims' Ride to the ruins of a nearby abbey. Among the cyclists are eccentric scientist George Jeffers, a fellow at St Frideswide's College, retired college porter Ned Canning and Jeffers' son Tom.


As St Frideswide's prepares to announce a new science building funded by Finn's Soft Earth Systems, George Jeffers refuses to attend, claiming his invention Kernel Logic, which is behind Finn's new air traffic control system, is flawed and potentially lethal. Despite the pleadings of Finn, university development officer Jonathan Canning and college master Melville Dodgson, Jeffers threatens to go public about the "glitch".


Meanwhile Tom's mother Melanie fears her son and ex-husband are besotted with school teacher Emily Harte. The villagers are shocked when Emily is killed by a hit and run driver while riding Jeffers' new bicycle. The motorist reversed over Emily's body after the accident - it's murder. Barnaby wonders if the outspoken Jeffers was the real target.


Finn tells Melanie he is not prepared to lose the millions he has invested in Kernel Logic. He demands support from Jonathan, who's in line to be the next master. Finn, Jonathan and the master all claims their disagreements with Jeffers would never lead to murder. As reporter Ursula Carroll interviews Jeffers, a webcam at his cottage alerts him to a break-in. He rushes back and is struck by the intruder.


Jones discovers the paint on Jeffers' bicycle matches a Jaguar in Finn's collection but the car is undamaged. Jeffers goes back to work and tells his students about the glitch, prompting Jonathan to set off the fire alarm to silence him.


Garage boss Daniel Snape discovers something about the hit-and-run car but before he can tell anyone he is killed. Meanwhile Barnaby confronts Finn and he admits being the intruder at Jeffers' home. He wanted to see an article Jeffers had written about the glitch.


On the day of the Pilgrim's Ride, Joyce and Cully join the cyclists, while Jones and Stephens pedal to keep up with Jeffers. As Barnaby makes a surprise discovery about the car and the Bucketman, Jeffers disappears. Will the police get to him before the killer?