‘Every case is different [...] routine kills. I demand from my people that they look at every case from scratch as if they know nothing and it’s from looking at a case from that way that you will see some details. Some specific elements that make a case unique. [...] Never exclude anything [...] everything is possible’, Alain Remue, Head of the Belgium Federal Police's Missing Person's Unit (17 May 2013). Alain Remue, in a recent address to a European meeting of researchers on missing people, reminds us of the need to regard each missing person episode as a unique single event. Understanding the way in which people interact with the environments around them is an integral part of comprehending the behaviour of missing people and their unique journeys, and as such is the focus of this chapter. Whenever a person is reported missing to the police, there is an obvious need to locate an individual in space and time. The Association of Chief Police Officers (ACPO) provide a definition of ‘missing’ equating to '… anyone whose whereabouts cannot be established …', and a definition of ‘absent’ as 'a person not at a place where they are expected or required to be' (ACPO 2013: 5) clearly indicating that when someone is reported as missing to the police, it is because their geographical location at that moment in time is unknown or uncertain. To complicate matters, the individual may not be static in their situation or behaviour, and may move over time, through space, navigating the environment on an evolving journey, which could also be considered uncertain in terms of its intentionality (Stevenson et al. 2013). Consequently, searching for a missing person can be a complicated process for any agency, involving interpreting the interplay of spatial, environmental and human elements at stake. In this chapter, we elaborate these complexities, and seek to use recent research evidence to shed new light on missing adult geographies and journeys