Horgan's career breakthrough was "Pulling", which she co-wrote with Dennis Kelly and starred in. She played Donna, an irresponsible marketing manager who calls off her wedding at the last minute, and one of three women sharing a flat in Penge, south London. It was noted for its broad humour about sex and the consumption of alcohol. "Pulling" was first shown on BBC Three in 2006, then repeated on BBC Two in 2008. The six-episode series became a ‘sleeper hit’, which gained iconic status with fans and was lauded by critics. A second series of six episodes ran March–April 2008 on BBC Three.