
Will develops an elaborate scheme to date "single mums" by attending a support group and pretending he has a two year-old child named "Ned." It actually works and he begins dating a woman from the support group he is attending. They end up on a Saturday outing to a park. The woman informs Will on their way out the door that they are taking her friend's geeky teenage son "Marcus" (Hoult) on the outing with them because his mother (Toni Collette) is not feeling well. His mother is something of a hippie and gives him a loaf of bread to take on the picnic. It is hard as a rock and won't break when Marcus tries to feed the ducks with it. In desperation, he finally throws the entire loaf into the pond and kills a duck with it. Forever after that he calls that day "the dead duck day."
Marcus is very disconcerted by his mother's suicide attempt. He is bullied at school and doesn't have any friends. He is such a target for bullies that even the other geeky kids don't feel safe hanging around him. He also realizes that the only person he really has in the world is his mother, and she is unstable. He says to himself that one person is not enough. "You need backup." So Marcus turns to Will, the "island" man, and starts dropping by his apartment after school. At first Will is resistant, but eventually takes a liking to Marcus.
After he lets Marcus in, Will takes a fancy to another beautiful "single mum" named "Rachel" (Rachel Weisz) and wants her to be his girlfriend. He wishes that he was "in any way interesting" to make him more appealing to her. He interjects a comment about Marcus in a conversation she is having with someone else, and she assumes that Marcus is Will's son. Not having learned his lesson yet, Will allows her to go on believing that, even when he brings Marcus over to her house for a Saturday afternoon. During that little event, Marcus is forced to associate with Rachel's son Ali (Augustus Prew), who is one of the kids bullying Marcus at school. When he threatens to cut Marcus into little pieces if he doesn't stop his "father" from dating Rachel, Marcus goes running from the house, and Rachel is forced to do some advanced single parenting.
Will, fresh from this stinging rejection, blames Marcus for messing up his relationship and says he can't help him with "real things" like his mother's depression. Marcus gets upset and decides the only way to make his mother happy is to sing "Killing Me Softly" in front of his entire school at a talent show, playing a tambourine that his mother gave him for Christmas.
When they get there, Will pleads with Marcus not to perform and tells him that he cannot make his mother happy, and she has to do that for herself. Marcus disagrees and goes out on stage. He begins a timid performance and is about to be laughed off stage when Will shows up on stage with an electric guitar and gives a humorous (but a little more "hip") performance--for which he takes an apple to the head from a heckling student in the crowd. His performance saves the day for Marcus. Rachel is in the crowd and is impressed by Will's willingness to make a fool out of himself to get Marcus through his moment of humiliation. She gets back together with him and Marcus develops some sort of relationship with the first crush. The closing scene of the film is where they are all celebrating Christmas together as a hodgepodge of misfit people.
I also love that this movie is full of single parents who are finding their own ways through life, and a confirmed bachelor who develops a parental kind of love for a young kid. They are figuring out parenting mostly on their own. When I was a mid-single, I often said, "We are the Island of misfit toys." I think it helps for mid-singles to be together and give each other support. It is tempting to draw a little bubble around ourselves and our children and stay isolated. Having been through significant traumas, it feels safer to close people out. But letting more people in is important. Letting love in is essential.