White, as a committed pacifist, made a career-long effort to find clever ways of injecting dramatic tension into his plots without glorifying violence. LIFEBOAT, like many of his books, does this partly through having a medic as the chief character - here Mercer, the new ship's doctor of the EURYDICE, one of a handful of ships that make regular runs from Earth to the moons of Jupiter carrying immigrants to a growing colony on Ganymede and materials to Earth's permanent space stations.
Space travel in this near-future has been classified as safe, where old-fashioned fussbudgets like Prescott, the first officer notorious for checking all possible anomalies, are considered tiresome nuisances - until EURYDICE terms out to have a fatally sick component installed as part of its propulsion system, and the drills for evacuating passengers to the escape pods become vital. (The diagnosis of EURYDICE's problem is very well written, from the crew's professionalism to the first cause, which turns out to be that a component of the wrong size was installed - such a major error that once it slipped through inspection, nobody noticed until it malfunctioned.)
The first third of the book introduces the ship, passengers, and problem, up to the evacuation of the EURYDICE. The remaining two thirds cover the problems of having a ship full of passengers stuffed at random into fourteen transparent lifepods, with limited air, merciless exposure to sunlight, and one-way radio communication with the Captain's pod (shared by Mercer, since the Captain is suffering from radiation poisoning that requires immediate treatment to prevent permanent damage). Mercer has to continually cajole, counsel, and comfort the passengers verbally without being able to directly intervene, and without being able to communicate privately with any of them, which is tricky considering some of the human complications of the evacuation.
One pod, for example, is occupied by one man and three young women, while another is occupied by the now-single Mrs. Matthewson and two increasingly aggressive men - and thanks to the transparent pod casings, none of them have any privacy or any escape from continual exposure to heat and light except by shedding excess clothing. Another pod's sole occupant is Mrs. Matthewson's ten-year-old son. Most of the married couples on the trip are split up into separate pods, just to make life a little *more* complicated. Mercer's communications with the passengers have to be *very* diplomatic indeed.
And, of course, the pods have to get clear of the dying EURYDICE, make course corrections at the hands of unskilled occupants, and await rescue without anyone losing control and causing either a fatal accident or a course adjustment that would amount to the same thing.
A lot of background detail has been provided to flesh out the characters. For instance, the late Mr. Matthewson was addicted to a drug that caused something like multiple personality disorder, so that his wife and son are still quite edgy. The Corries lost their own child to a fatal accident (an image that turns up in more than one of White's novels, including THE DREAM MILLENIUM) and are taking jobs on Ganymede to help them forget their troubles. Captain Collingwood's wife also works for the corporation, but back on Earth's launch facility, so Mercer knows exactly how much the Captain has to live for. As for Mercer himself, he's adjusting from being an almost-optional brand-new member of the ship's crew to being essential to everyone's survival.