Set in Singapore during the 1997 Asian financial crisis, Ilo Ilo chronicles the Lim family as they adjust to their newly arrived Filipina domestic helper, Teresa, (Angeli Bayani) who has come, like many other Filipinas, in search of a better life. The film’s Chinese title translates as "Mom and Dad Are Not Home".[7] The father, Teck, (Chen Tian Wen) works in sales for a glass company; the pregnant mother, Hwee Leng, (Yeo Yann Yann) works as a secretary for a shipping company that is down sizing; and the ten-year-old son, Jiale, (Koh Jia Ler) is a troubled delinquent.
At first, Jia Le and Teresa (known as 'Terry') exhibit a troubled relationship, when during a trip to the bookstore Jia Le places some unpaid merchandise in the maid's shopping bag causing her to be accused of theft. After being scolded by Terry, tensions rise, causing Jia Le to climb over the school fence at dismissal just to avoid his maid.
When the father loses his sales job, he conceals it from his wife, secretly smoking on the steps outside their apartment. After some time, unable to find work in a career position, he accepts a temporary job as a security guard monitoring an egg farm. As he continues to lose money in the stock market, in a moment of depression, he acknowledges their losses to his wife who lambasts him over his failure. As the family finances begin to descend deeper, familial tensions grow as Jiale continues to act out against his family and Terry. Upon the death of a neighbour who jumps from the roof of their apartment building, Jiale and Terry begin to kindle a relationship.
While the mother is desperate to stay employed as she continues to script termination letters at her job, Terry and Jiale become fast friends sparking the mother's jealousy as their relationship develops. Desperate at home, and emotionally neglected by her son, Hwee Leng attends a motivational seminar where she is moved by the optimistic words of the speaker and immediately purchases his full catalogue of motivational books and CDs. During a lunch break at work, she attempts to call the speaker using a phone number included on the seminar's flyer, and discovers the line has been disconnected and rerouted. Later that night while watching television, she learns that the motivational speaker has been arrested for fraud causing Hwee Lang to break down in the presence of her confused husband as more money is lost.