When recently-widowed Vivien announces her love for a new man, Mark, it throws her family of adult children into chaos. The siblings' growing suspicions about Mark are fuelled by rising tensions in their own lives: Helen's focus on her high-powered job has led to a deep rift in her marriage, Jake's gambling debts have caused his wife and kids to leave him, and Natalie is lying to everybody about her secret relationship.

Helen, Jake and Natalie are shocked when they discover Vivien plans to sell their childhood home and go travelling with Mark. Meanwhile, each of the siblings' personal problems are growing: Helen's actions at work have severe repercussions in her marriage, Jake is stunned to hear that Leila might be moving on from him, and Natalie's affair starts to threaten her physical safety. To make matters worse, Vivien and Mark make a snap decision on holiday that almost breaks neighbour Mary's heart.

Vivien and Mark plan their trip to India, but the children's ongoing distrust of Mark starts to put a strain on the couple's relationship - despite neighbour Mary's attempts at reassurance. Meanwhile, the siblings' private lives are unravelling: Helen's husband and daughter have both walked out on her; Natalie is close to a breakdown over her situation with Tony; and Jake increasingly relies on Stella for advice on getting back together with Leila.

Vivien tries to dismiss her children's fears about Mark, even as serious doubts creep into her mind. Jake's chances of reconciling with Leila suffer a potentially fatal blow. Helen is desperate to patch things up with George, even as her career hangs in the balance. While Natalie stands on the precipice between having and losing everything with Tony. It all comes to a head at Vivien's 70th birthday party, where events spiral into terrible tragedy.