Intruder alert
From Tardis Wiki, the free Doctor Who reference
Intruder alert was an alert status in facilities which were sounded when an intruder was detected.
An "Intruder Alert Level 5" was declared in a Department virtual reality detention facility when a Jixen warrior penetrated the prison. (TV: Regeneration [+]Loading...["Regeneration (TV story)"])
The Thirteenth Doctor mistook the doorbell in Graham and Grace's house for an intruder alert. (TV: Resolution [+]Loading...["Resolution (TV story)"])
