Act I
The show opens with Bert, a man of many professions, introducing the audience to Cherry Tree Lane ("Chim Chim Cheree"). Number 17 is where the Banks family lives: George (A Banker) and Winifred (former American Actress) Banks, their two children Jane and Michael, their cook, Mrs Brill and their odd-job man, Robertson Ay. Things are not going well, for Jane and Michael are out of control and as the show starts, their latest nanny, Katie Nanna, storms out. The children decide to write the advertisement for a new nanny ("The Perfect Nanny"), but George Banks has a very different idea of what constitutes the perfect nanny and he tears up the piece of paper and throws it in the fireplace. Within moments Mary Poppins arrives and takes charge of the Banks children, having every confidence in her own qualifications and merits ("Practically Perfect").
On the children's first outing to the park, they meet Bert and, despite their reservations about his ragged clothes and dirty face, Mary teaches them that they must learn to look past appearances. To illustrate the point, Mary brings the park statues, including a mythological figure named Neleus, to life ("Jolly Holiday").
While Mary manages the children, other problems lie with their parents. Winifred Banks is aware that she is somehow disappointing both her children and her husband. George Banks, on the other hand, can't understand why she finds the role of wife and mother so difficult. In an effort to please her husband, Winifred sends out invitations for a smart tea party. The children inadvertently sabotage the kitchen preparations, but Mary Poppins sorts it out with a lesson ("A Spoonful of Sugar"). However, it is then revealed that none of the invitees are coming.
Mary takes the children to visit their father at the bank where he works ("Precision and Order"). There George is busy dealing with possible investment clients: first an ambitious man named Von Hussler who has an elaborate money-making scheme, and then a middle-class man named Northbrook who has a simple factory project. George is furious when Mary turns up with the children, but an innocent question asked by Jane makes him realise how much his values have changed ("A Man Has Dreams") since he was an idealistic young man. He then decides to accept Northbrook's project, and rejects Von Hussler's.
Outside St. Paul's Cathedral, Mary introduces the children to the Bird Woman ("Feed the Birds"). Jane is suspicious of her, but Michael responds to the Bird Woman and throws crumbs for the birds. On the trip home, the children meet the enigmatic Mrs. Corry who runs a magic sweet shop that also sells words ("Supercalifragilisticexpialidocious").
The children return home in high spirits, unaware that things have gone wrong for their father. Unknown to them, George's decision to reject Von Hussler has cost the bank dearly, and he is suspended without pay. George explodes with rage at the children and they are sent to the nursery.
Reacting to her father's outburst, Jane flies into a fury, ignoring Mary Poppins' words of warning about controlling her temper. The frightening consequence of her anger becomes apparent as Jane and Michael's toys take on a life of their own and teach the naughty children a lesson ("Playing the Game").
Realising that Jane and Michael still have a lot to learn, Mary decides to leave Cherry Tree Lane ("Chim Chim Cheree") to bring them to their senses. Her distraught charges find a note bidding them 'au revoir' ("goodbye", "see ya" in French), which they learn from Mrs. Brill, means that perhaps they will see Mary Poppins again.
