Pharmaceutical maintenance man Martin Hurdle livens up his tedious workdays by doing celebrity impressions. He learns that he has an 18-year-old son named Steven and, pausing only to impersonate Ronnie Corbett stuck in a pillar box, joins the lad for lunch. The meeting is a success but when Martin's attempt at getting a promotion to impress Steven backfires, he uses his mimicry skills to get revenge.

Martin rings his ex Dionne to complain about her keeping Steven a secret before being given dubious dating tips by desperate newsagent Neil. Come the weekend, he heads off for the pub where he puts on a convincing accent to fool the residents. Steven tracks him down and is amazed by his father's talent, suggesting he profit from it.

After the flood damage caused by Jean from upstairs leaving the bath taps on, Martin takes his computer for repair and narrowly avoids being arrested when a photo of himself as an infant is found on it. His plans to meet Steven at the zoo are interrupted so Martin does an impression of Sir David Attenborough as he escorts blind Della around and gives commentary on the animals. He moves in with Neil, who arranges a disastrous double date but introducing Steven to his family goes more smoothly.

Martin and Neil comfort a recently dumped Jean, and Martin returns to the flat to share a - platonic - bed with her. Steven gets him a job doing celebrity voices for SatNav and whilst the engineer is out, Martin ad-libs and is caught on the security camera. His impressions end up onlinr and he becomes an anonymous celebrity with a possible television career.

Martin prepares for his television debut though, thanks to Jean's makeover, his skin is considerably darker and on the eve of the appearance, he loses his voice. Neil takes him to a doctor, who diagnoses nerves but gives him tablets nonetheless. The voice returns as Martin makes it to the studio and finds himself in a talent contest pitted against a clever dog.