Summer arrives in Montauban, with its vacations, its barbecues... and the "Summer Triathlon," a popular, televised competition. Christian, a divorced businessman trading in smalltime schemes, has only one joy in his life: his twelve-year-old daughter. Out of love for her and to make up for all his petty lies and tall tales, he accepts to participate in this great sports event. The day he meets Christine, a single, pregnant mother, everything seems to coincide for Christian to set out in a new direction...