Sir David Jason has reprised his iconic role as the legendary Detective Inspector Jack Frost for the last time ever in a two-part finale of A Touch of Frost. The two-part film entitled If Dogs Run Free follows Frost's battle to convict Gerry Berland, a dangerous criminal masquerading as a successful businessman. He's been evading prison for years and, tenacious as ever, Frost is determined to send him down. Tipped off by RSPCA-officer, Christine Moorhead (Phyllis Logan), Frost raids an illegal dogfight organised by Berland, but fails to trap him. When a scuffle results in the murder of a teenage boy, to which Christine is the only witness, the case against Berland becomes more pressing. As Frost protects Christine from the mounting harassment of Berland's thugs, he finds himself falling for her. Will Frost find love in this concluding story?