Michael (Steven Robertson) has cerebral palsy and a speech impairment that makes it nearly impossible for anyone at Dublin's Carrigmore Home for the Disabled to understand anything he says. After his mother died, his father abandoned him, so now Michael feels very isolated and lonely, even though he is mobile in his wheelchair.

His life makes a gigantic turnaround when Rory O'Shea (James McAvoy) arrives at Carrigmore. He has Duchenne muscular dystrophy, a degenerative muscle-wasting condition; all he can control is two of his fingers and partial movements of his head. Rory has a special gift that is a life-saver for Michael: he can understand what he is saying and immediately amazes everyone, including Eileen (Brenda Fricker), the inflexible supervisor of the place. She takes a dim view of the newcomer's rebellious nature which is evident in his spiked hair, sarcasm, and propensity to play raucous music in the middle of the night.

Rory and Michael become friends and decide to have some fun together. They go to a pub where they meet two girls. Later they are hassled at the door of a nightclub but Rory manages to get them in by giving a speech about the rights of the disabled. On the dance floor, they whirl in their wheelchairs. They are both bedazzled by Siobhan (Romola Garai) whom they met earlier at the pub.

Rory is desperate to get out of Carrigmore which limits his freedom and puts a block in the way of his three immediate goals — to get drunk, to get arrested, and to get laid. But for the third time, he is turned down by a board for an independent living grant. They are not impressed with his abrasive personality and wild ways. Rory then comes up with the idea of confronting Michael's rich but negligent father (Gerard McSorley) and asking him to pay for an apartment for the two of them. It works, and they move into a custom-made place where they each have a room. Rory calls their new home "cripple heaven."

Both young men are delighted when they learn that Siobhan works in a supermarket: they offer her a job as their paid helper. But things get very complicated when Michael falls in love with her. And of course, Rory is attracted to her as well but plunges into sadness when he sees that Michael has no way of winning the heart of this beautiful young woman.

Damien O'Donnell directs this drama written by Jeffrey Caine. We have all known larger-than-life characters who roar into our lives and boisterously proclaim their presence and power and imagination. James McAvoy makes Rory into the kind of person who is original for the rest of us — a life force determined to leave his mark wherever he goes. Although he is sometimes cruel to Michael; in the last analysis, he does manage to open up this stunted and alienated young man to a much wider sense of what he can do and accomplish in life. Watching this transformation take place before our eyes is both a blessing and a delight.