A siege has developed at the Mt. Thomas hospital. While the armed and desperate Nerida Davidson and Jason Bennett hold Maggie and Wayne on the inside, the rest of the Heelers lay in wait on the outside of the building.
Meanwhile, bushfires ring the township making outside help a forlorn hope. The bandits' objective is to get their compatriot, Matt, out of the hospital and away, but this is not made any easier by his gradually worsening medical condition. When captured, Matt swallowed a handful of map pins in order to get to the hospital, a soft target from which he could be more easily rescued.
The situation is further complicated by the presence of mother-to-be Augusta Torrini and her emotional, hot-blooded husband, Sergio. When Wayne bravely tries to overcome the bandits he ends up pistol whipped and chained to a hospital bed. Maggie, Dr. Zoe Hamilton and Nurse Tracy Mitchell play a dangerous game of bluff to try to and get Augusta to safety.
Adam, meanwhile, comes up with some disconcerting information about Jason. It seems that as a teenager he quite literally got away with murder.
Zoe prevails on the bandits to let most of their hostages free, but they insist on keeping Wayne, Tracy and Maggie. Nerida is desperately frightened for her sick brother and seems amenable to good sense, but the psychopathic Jason has quite different ideas. Communication between the bandits inside the hospital and the police outside is even more difficult when Jason has a fit of temper and smashes Wayne's two-way radio.
As the fire rages outside, the situation in the hospital becomes more and more tense. Cut off from outside help and with Wayne bound and unconscious, Maggie has to fall back on her own resources. She tries the psychological approach and discovers that Nerida and Jason are a couple of disaffected private school kids, yuppies who are trying to set themselves up for life with a "once-only withdrawal" from a bank. Jason aims to get out of the hospital back to the hobby farm where they have stashed the loot from their bank job. Maggie tries to counter this by threatening the imminent arrival of the SOG ("coppers from hell"). The resumption of power supplies, however, enables Jason to discover the real situation. They are cut off and there is little chance of the SOG, or anybody else, getting through. Jason decides to go while the going's good and there is nothing the Heelers can do to stop them.
Meanwhile, isolation proves to be a problem for Augusta as lack of transportation forces her to have her baby in Tom' office at the police station. A baby boy is delivered by Zoe Hamilton, using Chris and Adam as midwives.
Nerida and Jason make their way back to the hobby farm, but not before personal tragedy and unforeseen circumstances intervene.