The notoriously single and not-so-successful womanizer Max has settled down perfectly into his bachelor life when suddenly the enchanting Lisa, sister of his flatmate and partner Ulli, appears on his doorstep and asks to stay for the next four weeks. Nothing better than that, Max thinks to himself and smells prey. But in no time at all, Lisa's appeal is gone when Max realizes that she hasn't come alone: she has her sweet baby Maya with her - and that's the last straw for Max. How is he and Ulli supposed to win the city council's architectural competition if a toddler is constantly bawling in their ears? Ulli insists on helping Lisa and puts a gun to Max's head: either mother and child can stay - or he will leave the apartment they share.